8_applications of derivatives.pdf
TRANSCRIPT
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:.6 Jdrcvftcvd fs f rftd ndfsurd
Cl y > l(x) cs f lubetc`b l x, tmdbjx
jy r l (x) rdprdsdbts tmd rftd-ndfsurd l y wctm rdspdet t` x.
(f) rdprdsdbts)x('l`rjx
jy
7xx 7>
tmd rftd `l emfbkd `l y w.r.t. x ft x > x7.
(h) Cl y cberdfsds fs x cberdfsds, tmdbjx
jycs p`sctcvd fbj cl y jderdfsds fs x cberdfsds, tmdb
jx
jycs bdkftcvd.
(e) Nfrkcbfo E`st (NE) cs tmd cbstfbtfbd us rftd l emfbkd l t tfo e st wctm rdspdet t tmd bunhdr l ctdns
pr`juedj ft fb cbstfbt.
(j) Nfrkcbfo Xdvdbud (NX) cs tmd cbstfbtfbd us rftd l emfbkd l t`tfo rdvdbud wctm rdspdet t` tmd bunhdr
`l ctdns s`oj ft fb cbstfbt.
:.8 Zfbkdbts fbj b`rnfo
(f) Z` lcbj tmd dquftc b l tmd tfbkdbt t` tmd eurvd y > l(x) ft tmd kcvdb p cbt W(x6, y
6), pr`eddj fs ubjdr 1
(c) Lcbjjx
jylr`n tmd kcvdb dquftc`b y > l(x).
(cc) Lcbj tmd vfoud ljx
jyft tmd kcvdb p`cbt W (x
6, y
6), odt n >
6
6
yy
xxjx
jy
>>
.
(ccc) Zmd dquftc`b l tmd rdqucrdj tfbkdbt cs y y6> n (x x
6).
Cb pfrtceuofr, cl >
6
6
yy
xxjx
jy
>>
j`ds b`t dxcst, tmdb tmd dquftc`b l tmd tfbkdbt cs x > x
6.
(h) Z` lcbj tmd dquftc b l tmd b rnfo t` tmd eurvd y > l(x) ft tmd kcvdb p`cbt W(x6, y
6), pr`eddj fs ubjdr 1
(c) Lcbjjx
jylr`n tmd kcvdb dquftc`b y > l(x).
(cc) Lcbj tmd vfoud ljx
jyft tmd kcvdb p`cbt W(x
6, y
6).
(ccc) Cl n cs tmd so pd l tmd b rnfo t` tmd kcvdb eurvd ft W, tmdb n >
6
6
yy
xxjx
jy
6
>>
.
(cv) Zmd dquftc`b l tmd rdqucrdj b`rnfo cs y y6> n (x x
6).
Cb pfrtceuofr cl,
6
6
yy
xxjx
jy
>>
> 7, tmdb tmd dquftc`b `l tmd b`rnfo ft W cs x > x
69 fbj cl >
6
6
yy
xxjx
jy
>>
j`ds b`t dxcst, tmdb tmd dquftc`b `l tmd b`rnfo ft W cs y > y6.
Fbkod l cbtdrsdetc`b l tw` eurvds
Zmd fbkod l cbtdrsdetc`b l tw` eurvds cs tmd fbkod hdtwddb tmd tfbkdbts t` tmd tw` eurvds ft tmdcr p`cbt
`l cbtdrsdetc`b.
Cl n6fbj n8frd tmd so`pds l tmd tfbkdbts t` tmd kcvdb eurvds ft tmdcr p`cbt l cbtdrsdetc`b W(x6, y6), tmdb
tmd (feutd) fbkod qhdtwddb tmd eurvds cs kcvdb hy
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tfb q>86
86
nn6
nn
+-
.
Cb pfrtceuofr 1
(c) cl n6n
8> 6, tmdb eurvds frd sfcj t` eut rtm`k`bfooy.
(cc) cl n6> n8, tmd eurvds t`uem dfem `tmdr.
:.5 Cberdfscbk fbj jderdfscbk lubetc bs
Cl l cs f rdfo vfoudj lubetc`b jdlcbdj cb fb cbtdrvfo J ( f suhsdt l X), tmdb l cs efoodj fb cberdfscbk lubetc`b
cb fb cbtdrvfo J6(f suhsdt `l J) cll l`r foo x
6, x
8J
6, x
6? x
8 l(x
6) l(x
8) fbj l cs efoodj f strcetoy
cberdfscbk lubetc`b cb J6cll l`r foo x
6, x
8J
6, x
6? x
8 l(x
6) ? l(x
8).
Ucncofroy, l cs efoodj f jderdfscbk lubetc`b cb fb cbtdrvfo J8(f suhsdt l J) cll l`r foo x
6, x
8J
8, x
6? x
8
l(x6)l(x
8) fbj l cs efoodj f strcetoy jderdfscbk lubetc b cb J
8cll l r foo x
6, x
8J
8, x
6? x
8l(x
6) 2 l(x
8).
Cb pfrtceuofr, cl J6> J tmdb l cs efoodj fb cberdfscbk lubetc`b cll l`r foo x
6, x
8J, x
6? x
8
l(x6) l(x8)9 fbj l cs efoodj strcetoy cberdfscbk lubetc`b cll l`r foo x6, x8J, x6? x8 l(x
6) ? l(x
8). Fbfo k`usoy, cl J
8> J tmdb l cs efoodj f jderdfscbk lubetc`b cll l`r foo x
6, x
8J, x
6
? x8 l(x
6) l(x
8)9 fbj l cs efoodj strcetoy jderdfscbk lubetc`b cll l`r foo x
6, x
8J, x
6? x
8 l(x
6) 2
l(x8).
F lubetc`b wmcem cs dctmdr (strcetoy) cberdfscbk `r (strcetoy) jderdfscbk cs efoodj f (strcetoy) n`b`t`bce
lubetc b.
E`bjctc`bs l`r fb cberdfscbk r f jderdfscbk lubetc`b
Zmd`rdn 6. Cl f lubetc`b l cs e`btcbu`us cb Yf, h^, fbj jdrcvfhod cb (f, h) fbj
(c) l (x) 7 l`r foo x (f, h), tmdb l cs cberdfscbk cb Yf, h^
(cc) l (x) 2 7 l`r foo x (f, h), tmdb l cs strcetoy cberdfscbk cb Yf, h^.
Zmd`rdn 8. Cl f lubetc`b l cs e`btcbu`us cb Yf, h^, fbj jdrcvfhod cb (f, h) fbj
(c) l (x) 7 l`r foo x (f, h), tmdb l cs jderdfscbk cb Yf, h^
(cc) l (x) ? 7 l r foo x (f, h), tmdb l cs strcetoy jderdfscbk cb Yf, h^.
Cb lfet, cl f lubetc`b l(x) cs e`btcbu`us cb Yf, h^, jdrcvfhod cb (f, h) fbj
(c) l (x) 2 7 l r foo x(f, h) dxedpt l`r f lcbctd bunhdr l p`cbts wmdrd l (x) > 7, tmdb l(x) cs strcetoy
cberdfscbk cb Yf, h^.
(cc) l (x) ? 7 l r foo x(f, h) dxedpt l`r f lcbctd bunhdr l p`cbts wmdrd l (x) > 7, tmdb l(x) cs strcetoyjderdfscbk cb Yf, h^.
:.: Nfxcnf fbj Ncbcnf
Cl l cs f rdfo vfoudj lubetc`b jdlcbdj b J (suhsdt l X) tmdb
(c) l cs sfcj t` mfvd f nfxcnun vfoud cb J, cl tmdrd dxcsts f p`cbt x > e cb J suem tmft l(e) l(x)
l`r foo x J. Zmd bunhdr l(e) cs efoodj tmd (fhs`outd) nfxcnun vfoud `l l cb J fbj tmd p`cbt e cs
efoodj p`cbt l nfxcnf l l cb J.
(cc) l cs sfcj t` mfvd f ncbcnun vfoud cb J, cl tmdrd dxcsts f p cbt x > j cb J suem tmft l(j) l(x) l`r foo
x J. Zmd bunhdr l(j) cs efoodj tmd (fhs`outd) ncbcnun vfoud l l cb J fbj tmd p`cbt j cs efoodjp cbt l ncbcnf l l cb J.
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(f) O efo nfxcnf fbj o`efo ncbcnf
Cl l cs f rdfo vfoudj lubetc`b jdlcbdj b J (suhsdt l X), tmdb
(c) l cs sfcj t` mfvd f o efo (`r rdoftcvd) nfxcnf ft x > e (cb J) cll tmdrd dxcsts f p`sctcvd rdfo bunhdr
jsuem tmft l(e)l(x) l`r foo x cb (e j, e +j) c.d. l(e)l(x) l`r foo x cb tmd cnndjcftd bdckmh`urm``j`l e, fbj e cs efoodj p`cbt l o`efo nfxcnf fbj l(e) cs efoodj o`efo nfxcnun vfoud.
(cc) l cs sfcj t` mfvd o efo (`r rdoftcvd) ncbcnf ft x > j(cb J) cll tmdrd dxcsts s`nd p sctcvd rdfo bunhdrjsuem tmft l(j) l(x) l`r foo x (j j, j + j) c.d. l(j)l(x) l`r foo x cb tmd cnndjcftd bdckmh`urm``j`l j, fbj j cs efoodj p`cbt l o`efo ncbcnf fbj l(j) cs efoodj o`efo ncbcnun vfoud.
Kd`ndtrcefooy, f p`cbt e cb tmd j`nfcb l tmd kcvdb lubetc`b l cs f p`cbt l o`efo nfxcnf r o`efo
ncbcnf fee`rjcbk fs tmd krfpm l l mfs f pdfi r tr`ukm (efvcty) ft e.
(ccc) f p`cbt (cb J) wmcem cs dctmdr f p cbt l o efo nfxcnf r f p`cbt `l o`efo ncbcnf cs efoodj fb
dxtrdnd p`cbt, fbj tmd vfoud l tmd lubetc`b ft tmcs p`cbt cs efoodj fb dxtrdnd vfoud.
(h) Erctcefo ( r turbcbk) p`cbt
Cl l cs f rdfo vfoudj lubetc`b jdlcbdj `b J (suhsdt `l X), tmdb f p`cbt e (cb J) cs efoodj f erctcefo
(`r turbcbk r stftc`bfry) p`cbt l l cll l cs jclldrdbtcfhod ft x > e fbj l (e) > 7.
(e) W`cbt l cblodetc`b
F p`cbt W(e, l(e)) b tmd eurvd y > l(x) cs efoodj f p`cbt l cblodetc`b cll b bd scjd l W tmd eurvd ocds
hdo w tmd tfbkdbt ft W fbj b tmd tmdr scjd ct ocds fh`vd tmd tfbkdbt ft W. Zmus, f p`cbt wmdrd tmd eurvd
er`ssds tmd tfbkdbt cs efoodj f p`cbt l cblodetc`b.
Zmd`rdn. F lubetc`b l (`r tmd eurvd y > l(x)) mfs f p`cbt l cblodetc b ft x > e cll l (e) > 7, l (e) > 7 fbj
l (e) 7.
(j) [`ricbk ruods l`r lcbjcbk (fhs outd) nfxcnun fbj ncbcnun
Cl f lubetc`b l cs jclldrdbtcfhod cb Yf, h^ dxedpt (p`sschoy) ft lcbctdoy nfby p`cbts, tmdb t` lcbj (fhs`outd)
nfxcnun fbj ncbcnun vfouds fj`pt tmd l`oo`wcbk pr`edjurd 1
(c) Dvfouftd l(x) ft tmd p cbts wmdrd l (x) > 7
(cc) Dvfouftd l(x) ft tmd p cbts wmdrd jdrcvftcvd lfcos t` dxcst.
(ccc) Lcbj l(f) fbj l(h).
Zmdb tmd nfxcnun l tmdsd vfouds cs tmd fhs outd nfxcnun fbj ncbcnun l tmdsd vfouds cs tmd fhs outd
ncbcnun l tmd kcvdb lubetc`b l.
(d) [`ricbk ruods t` lcbj p`cbts l o efo nfxcnf fbj ncbcnf
6. O`eftd tmd p cbts wmdrd tmd kcvdb lubetc`b l cs ocidoy t` mfvd dxtrdnd vfouds 1
(c) Zmd p cbts wmdrd tmd jdrcvftcvd lfcos t dxcst.
(cc) Zmd turbcbk (erctcefo) p cbts c.d. tmd p`cbts wmdrd tmd jdrcvftcvd cs zdr .
(ccc) Dbj p`cbts l tmd j`nfcb cl l cs jdlcbdj cb f eo sdj cbtdrvfo Yf, h^.
Zmdsd frd tmd boy p`cbts wmdrd l nfy mfvd dxtrdnd vfouds, odt e hd fby bd suem p`cbt.
8. Cl l (e) j`ds b t dxcst hut l dxcsts cb bdckmh`urm` j l e, tmdb tmd l oo`wcbk tfhod jdserchds tmd
hdmfvc ur l tmd lubetc b l ft e 1
x sockmtoy ? e sockmtoy 2 e Bfturd l p`cbt
l '(x) + vd vd Nfxcnf
l '(x) vd + vd Ncbcnf
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5. Cl e cs f turbcbk p cbt c.d. l (e) dxcsts fbj l (e) > 7. Odt b8 hd tmd snfoodst p`sctcvd cbtdkdr suem
tmft l(b)(e) 7, tmdb tmd l`oo`wcbk tfhod jdserchds tmd hdmfvc`ur l tmd lubetc`b l ft e 1
b sckb `l l(b)(e) Bfturd `l tmd turbcbk p`cbt e
`jj + vd r vd Bdctmdr nfxcnf b`r ncbcnf
dvdb + vd Ncbcnfdvdb vd Nfxcnf
Fotdrbftcvdoy, cl ct cs jcllceuot t` lcbj tmd jdrcvftcvds l mckmdr rjdr tmdb tmd l`oo`wcbk tfhod jd-
serchds tmd hdmfvc`ur l tmd lubetc b l ft e 1
x sockmtoy ? e sockmtoy 2 e Bfturd l tmd turbcbk p`cbt
l '(x) + vd vd Nfxcnf
l '(x) vd + vd Ncbcnf
l '(x) + vd + vd Bdctmdr nfxcnf b`r ncbcnf
l '(x) vd vd Bdctmdr nfxcnf b`r ncbcnf
:. Zmd l oo`wcbk tfhods jdserchd tmd hdmfvc ur ft tmd dbj p cbts 9
Odt dbj p`cbt f.
x sockmtoy 2 f Bfturd l p`cbt
l '(x) + vd Ncbcnf
l '(x) vd Nfxcnf
Xckmt dbj p`cbt h.
x sockmtoy ? h Bfturd l p`cbt
l '(x) + vd Nfxcnf
l '(x) vd Ncbcnf
4. Lcbfooy, t` lcbj tmd fhs outd nfxcnun r fhs`outd ncbcnun l f lubetc`b l cb eo`sdj cbtdrvfo Yf, h^
9 lcbj tmd vfouds `l l ft tmd p cbts `l foo tmd tmrdd eftdk`rcds ocstdj fh`vd. Zmd nfxcnun `l tmdsd vfouds cs
tmd fhs outd nfxcnun fbj tmd ncbcnun l tmdsd vfouds cs tmd fhs outd ncbcnun l tmd lubetc b l cb Yf, h .
(l) L`r prfetcefo pr hodns b nfxcnf fbj ncbcnf
Cl f lubetc`b cs e`btcbu`us cb fb pdb cbtdrvfo (f, h) fbj ct mfs boy bd dxtrdnd p`cbt cb (f, h), tmdb ct csf p`cbt l fhs`outd nfxcnf r f p`cbt l fhs`outd ncbcnf fee`rjcbk fs ct cs f p`cbt l o efo nfxcnf r f
p cbt l o efo ncbcnf.
:.4 Fppr`xcnftc bs
Odt y > l(x) hd f lubetc`b `l x fbj jx hd f snfoo emfbkd cb tmd vfoud l x fbj jy hd tmd e`rrdsp`bjcbk
emfbkd cb tmd vfoud l y, tmdb jx >jx
jyjx.
* U`nd cnp`rtfbt tdrns
Fhs`outd drr`r.Zmd cberdndbtjx cb x cs efoodj tmd fhs`outd drr`r cb x.
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Dx.6 Zmd rfjcus `l fb fcr huhhod cs cberdfscbk ft tmd rftd `l8
6en/s. Ft wmft rf td cs tmd v`ound
`l tmd huhhod cberdfscbk wmdb tmd rfjcus cs 6 en 0
U`o. Odt r en hd tmd rfjcus `l fb fcr huhhod fbj \ en 5hd cts v`ound. Zmdb,
\ >5
: pr5 ..........(c)
Ct cs kcvdb tmftjt
jr>
8
6en/s
B`w, lr`n (c), wd mfvd
jt
j\> :pr8
jt
jr> :pr8
8
6> 8pr8
[mdb r > 6 en,
jt
j\> 8p(6)8> 8pen5/s
Zmus, tmd rftd l emfbkd l v ounds l tmd fcr huhhod cs 8pen5/s.
Dx.8 F hfoo``b, wmcem fowfys rdnfcbs spmdrcefo `b cbloftc`b, cs hdcbk cbloftdj hy punpcbk cb 377
euhce edbtcndtdrs `l kfs pdr sde`bj. Lcbj tmd rftd ft wmcem tmd rfjcus `l tmd hfoo``b
cberdfsds wmdb tmd rfjcus cs 64 en.
U`o. Odt r en jdb`td tmd rfjcus l tmd spmdrcefo hfoo``b fbj \ hd cts v`ound. Zmdb,
\ >5
:pr5 ........(c)
Ct cs kcvdb tmft jt
j\> 377 en5/s
Lr`n (c), wd mfvd
jt
j\> :pr8
jt
jr
jt
jr> 8r:
377
p> 8r
884
p
[mdb r > 64 en,
jt
jr> 8)64(
884
p>
p6
>88
;en/s
Zmus, tmd rftd ft wmcem tmd rfjcus l tmd hfoo` b cberdfsds cs88
;en/s, wmdb r > 64 en.
Dx .5 Lcbj tmd odfs t vf oud `l f suem tmft tmd lube tc`b l kcvdb hy l(x) > x8+ fx + 6 cs strcetoy
cberdfscbk cb (6, 8).
U`o. Mdrd, l (x) > 8x + f
B`w, 6 ? x ? 8 8 ? 8x ? :
8 + f ? 8x + f ? : + f ....(6)
B`w, l(x) cs fb cberdfscbk lubetc b, s` l (x) 2 7 l r x(6, 8)
8x + f 2 7 l`r x (6, 8) 7 ? 8x + f l`r x (6, 8)
U@O\DJ WX@HODUN
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FWWOCEFZC@BU @L JDXC\FZC\DU x8 x + 6 cs bdctmdr strcetoy cberdfscbk b`r strcetoy
jderdfscbk cb (6, 6).
U`o. [d mfvd, l(x) > x8 x + 6
l (x) > 8x 6
Zmd erctcefo vfoud l l(x) cs8
6
Efsd 6[mdb 6 ? x ?8
6
Cb tmcs efsd, 6?x?8
6 5?8x 6?7
l (x) ? 7
Zmus, l(x) cs jderdfscbk l`r 6 ? x ?8
6
Efsd 8 [mdb8
6? x ? 6
Cb tmcs efsd,8
6? x ? 6 6 ? 8x ? 8 7 ? 8x 6 ? 6
Mdbed, l (x) 2 7
U`, l(x) cs cberdfscbk l`r8
6? x ? 6
U`, cb tmd cbtdrvfo (6, 6), l(x) cs bdctmdr cberdfscbk b`r jderdfscbk.
Dx.4 Lcbj tmd p`cbts `b tmd eurvd y > x5ft wmcem tmd so`pd `l tmd tfbkdbt cs dqufo t` tmd y-
e``rjcbftd `l tmd p`cbt.
U`o. Odt tmd p`cbt l tfbkdbey hd (x6, y
6).
Zmd, so`pd l tmd tfbkdbt ft (x6, y
6) cs kcvdb Y ^
6
6
xx8
xx
x5cswmcem,jx
jyhy >
>
c.d., 86x5 .
Ucbed, tmd so`pd cs kcvdb t` hd dqufo t` y6,wd mfvd
86x5 > y6 ......(6)
Fs (x6, y
6) ocds `b tmd eurvd y > x5, wd mfvd
y6> 56x .......(8)
Lr`n (6) fbj (8), wd mfvd
86x5 >
56x
x6> 7, 5 fbj s y
6> 75> 7 r y
6> 55> 8;
Zmus, tmd rdqucrdj p`cbts frd (7, 7) fbj (5, 8;).
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Dx.< Lcbj tmd dquftc`b l tmd b`rnfo ft tmd p`cbt (fn8, fn5) l`r tmd eurvd fy8> x5.
U`o. Uo`pd l tmd tfbkdbt t` tmd eurvd fy8> x5ft tmd p`cbt (fn8, fn5) cs kcvdb hy
)fn,fn(
58jx
jy
Kcvdb fy8> x5
[d mfvd, 8fyjx
jy> 5x8
jx
jy>
fy8
x5 8
)fn.fn(
58jx
jy
>
f8
55
:8
fn
nf>
8
n5
_Uo pd l tmd b rnfo t tmd eurvd ft (fn8, fn5) cs n5
8.
Mdbed, tmd dquftc`b l tmd b`rnfo ft tmd p`cbt (fn8, fn5) t` tmd eurvd fy8> x5cs
y fn5> n5
8(x fn8)
c.d., 5ny 5fn:> 8x + 8fn8
c.d., 8x + 5ny fn8(8 + 5n8) > 7
Dx.; F ecreuofr ndtfo poftd dxpfbjs ubjdr mdftcbk s` tmft cts rfjcus cberdfsds hy 8%. Lcbj tmd
fppr`xcnftd cberdfsd cb tmd frdf l tmd poftd cl tmd rfjcus l tmd poftd hdl`rd mdftcbk cs 67 en.
U`o. Odt r en hd tmd rfjcus l tmd ecreuofr poftd fbj F hd cts frdf. Zmdb, F > pr8
jrjF
> 8prKcvdb r > 67 en (hdl`rd mdftcbk)
Odt Jr hd tmd cberdfsd cb tmd rfjcus l tmd ecreuofr poftd (fltdr mdftcbk) fbj JF hd tmd e`rrdsp`bjcbkcberdfsd cb frdf.
Zmdb, Jr > 8% `l 67 en
>677
8 67 en > 7.8 en
L`r, r > 67 en, Jr > 7.8 en
JF >jr
jF.Jr
> 8pr . (7.8) sq en > 8p(67) . (7.8) sq en > :psq en
Dx.= Lcbj tmd fppr`xcnftd emfbkd cb tmd t`tfo surlfed frdf `l f rckmt ecreuofr e`bd, wmdb tmd
rfjcus r rdnfcbs e`bstfbt wmcod tmd fotctujd m emfbkds hy .
U`o. Odt s jdb`td tmd t`tfo surlfed frdf l tmd rckmt ecreuofr e`bd. Zmdb,
888 r)mr(rs 86
p++p>
Ucbed r rdnfcbs e`bstfbt, s efb hd rdkfrjdj fs f lubetc`b l m boy.
[d mfvd Js > jmjs
.Jm
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Js > f
+
+
p.7
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8/10/2019 8_Applications of derivatives.pdf
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V.67 L`r tmd eurvd y > :x5 8x4, lcbj foo p`cbts ft wmcem tmd tfbkdbt pfssds tmr`ukm tmd rckcb.
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V.6; F squfrd tfbi l efpfecty 847 euhce ndtdrs mfs t` hd juk ut. Zmd e`st l tmd ofbj cs Xs. 47 pdr sq. n.
Zmd e`st `l jckkcbk cberdfsds wctm tmd jdptm fbj l`r tmd wm od tfbi e`st cs Xs :77 m 8, wmdrd m ndtrds
cs tmd jdptm l tmd tfbi. [mft sm`uoj hd tmd jcndbsc`bs l tmd tfbi s` tmft tmd e`st hd ncbcnun 0
V.6= F adt `l fb dbdny cs loycbk fo bk tmd eurvd y > x 8+ 8. F s`ojcdr cs pofedj ft tmd p`cbt (5, 8). [mft cs tmd
bdfrdst jcstfbed hdtwddb tmd s`ojcdr fbj tmd adt 0
V.63 F nfbulfeturd efb sdoo x ctdns ft f prced l Xs (847 x) dfem. Zmd e`st l pr`juecbk x ctdns cs Xs(8x8 47x + 68). Jdtdrncbd tmd bunhdr l ctdns t` hd s`oj s` tmft md efb nfid nfxcnun.
V.87 Zmd e`st l ludo l`r rubbcbk f hus cs pr`p`rtc`bfo t` tmd squfrd l tmd spddj kdbdrftdj cb in/mr. Ct e`stsXs := pdr m`ur wmdb tmd hus cs n`vcbk wctm f spddj l 87 in/mr. [mft cs tmd n`st de`b`ncefo spddj cl
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8/10/2019 8_Applications of derivatives.pdf
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FWWOCEFZC@BU @L JDXC\FZC\DU66
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V.6 Lcbj tmd cbtdrvfos cb wmcem tmd lubetc`b l(x) > x5 8x5 3x8+ 68x + 57 cs
(c) cberdfscbk (cc) jderdfscbk. YE.H.U.D. 8776^
V.4 Tscbk jclldrdbtcfos, lcbj fppr`xcnftd vfoud l 8 f8fbj x8+ y8> 8f8t`uem dfem tmdr. YE.H.U.D. 8778^
V.; F wcbj`w cs cb tmd l`rn l rdetfbkod fh`vd wmcem tmdrd cs sdnc-ecreod. Cl pdrcndtdr l wcbj`w cs p en,
sm`w tmft wcbj`w wcoo foo w tmd nfxcnun p`sschod ockmt boy wmdb tmd rfjcus l sdnc-ecreod cs:
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YE.H.U.D. 8778^
V.= Cl y > x:+ 67 fbj x emfbkds lr`n 8 t` 6.33. Lcbj tmd fppr`xcnftd emfbkd cb y. YE.H.U.D. 8778^
V.3 Um`w tmft rdetfbkod l nfxcnun frdf tmft efb hd cbserchdj cb f ecreod l rfjcus r cs f squfrd l
scjd r8 . YE.H.U.D. 8778^
V.67 F hfoo `b wmcem fowfys rdnfcbs spmdrcefo cs hdcbk cbloftdj hy punpcbk cb kfs ft tmd rftd l 377 en5/sde. Lcbj
tmd rftd ft wmcem tmd rfjcus `l hfoo `b cs cberdfscbk wmdb rfjcus l hfoo `b cs 64 en. YE.H.U.D. 8775^
V.66 F wcbj`w cs cb tmd l rn l f rdetfbkod surn`ubtdj hy f sdnc-ecreod. Cl tmd pdrcndtdr l tmd wcbj`w cs 677 n, lcbj tmd
jcndbsc`bs l tmd wcbj`w s` tmft nfxcnun ockmt dbtdrs tmr`ukm tmd wcbj`w. YE.H.U.D. 8775^
V.68 F pfrtceod n`vds fo`bk tmd eurvd y >5
8x5+ 6. LCbj tmd p`cbts `b tmd eurvd ft wmcem y-e``rjcbftd cs
emfbkcbk twced fs lfst fs x-e``rjcbftd. YE.H.U.D. 8775^
V.65 L`r tmd eurvd y > :x5 8x4, lcbj foo p`cbts ft wmcem tfbkdbt pfssds tmr`ukm rckcb.
YE.H.U.D. 8775^
V.6: F squfrd pcded l tcb l scjd 6= en cs t` hd nfjd cbt` f h`x wctm`ut f t`p hy euttcbk f squfrd pcded lr`n
dfem e`rbdr fbj l`ojcbk up tmd lofps. [mft sm`uoj hd tmd scjd squfrd t` hd eut ll s` tmft v`ound l tmd
h x hd nfxcnun 0 Fos` lcbj tmd nfxcnun v ound l tmd h`x. YE.H.U.D. 8775^
V.64 Lcbj tmd cbtdrvfos b wmcem lubetc`b l(x) > 8x6
x
+cs (c) Cberdfscbk (cc) Jderdfscbk.
YE.H.U.D. 8775^
V.6< Lcbj tmd cbtdrvfos cb wmcem tmd lubetc`b l(x) > x5 6 e`sq, y > q scb qftq> :p .YE.H.U.D. 877:^
V.6= Lcbj tmd cbtdrvfos cb wmcem tmd lubetc b l(x) >x
6x: 8 +, x 7 cs
(c) cberdfscbk (cc) jderdfscbk. YE.H.U.D. 877:^
V.63 Lcbj tmd dquftc`b l tfbkdbt fbj b`rnfo t` tmd eurvd y > x8+ :x + 6 ft tmd p`cbt wm`sd x-e``rjcbftd cs
5. YE.H.U.D. 877:^
V.87 Zmd v`ound l spmdrcefo hfoo` b cs cberdfscbk ft tmd rftd `l 84 en5/sde. Lcbj tmd rftd `l emfbkd l cts
surlfed frdf ft tmd cbstfbt wmdb cts rfjcus cs 4 en. YE.H.U.D. 877:^
V.86 Lcbj tmd cbtdrvfos cb wmcem lubetc`b l(x) > 8x5
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8/10/2019 8_Applications of derivatives.pdf
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V.85 Zmd surlfed frdf l f spmdrcefo huhhod cs cberdfscbk ft tmd rftd l 8 en8/s. Lcbj tmd rftd ft wmcem tmd
v`ound l tmd huhhod cs cberdfscbk ft tmd cbstfbt cts rfjcus cs < en. YE.H.U.D. 8774^
V.8: F wcrd l odbktm 5< en cs eut cbt` tw` pcdeds bd l tmd pcdeds cs turbdj cb tmd l`rn l f squfrd fbj tmd
`tmdr cbt` f ecreod. [mft sm`uoj hd tmd odbktms `l dfem pcded s` tmft tmd sun `l tmd frdfs `l tw` hd
ncbcnun 0 YE.H.U.D. 8774^
V.84 Wr`vd tmft tmd ocbdf
x+
h
y> 6 cs f tfbkdbt t tmd eurvd y > hdx/f, ft tmd p`cbt wmdrd tmd eurvd euts y-fxcs.
YE.H.U.D. 8774^
V.8< Fb `pdb h`x wctm f squfrd hfsd cs t` hd nfjd `ut `l f kcvdb cr`b smddt `l frdf 8; sq. n. Um`w tmft tmd
nfxcnun v`ound l tmd h`x cs 65.4 eu. n. YE.H.U.D. 8774^
V.8; Lcbj tmd cbtdrvfos cb wmcem tmd lubetc`b l(x) > 8x5 5x8 5 8 fbj y
6
2 7. Fos lcbj tmd p cbts l cbtdrsdetc b wmdrd h tm tfbkdbt fbj b`rnfo eut tmd x-fxcs. YE.H.U.D. 8774^
V.83 Lcbj f p`cbt b tmd pfrfh`of l(x) > (x 5)8, wmdrd tmd tfbkdbt cs pfrfoodo t` tmd em`rj a`cbcbk tmd p`cbts
(5, 7) fbj (:, 6). YE.H.U.D. 8774^
V.57 Lcbj tmd dquftc`b l tmd ocbd tmr`ukm tmd p`cbt (5, :) wmcem euts lr`n tmd lcrst qufjrfbt f trcfbkod lncbcnun frdf. YE.H.U.D. 8774^
V.56 Um`w tmft tmd nfxcnun v`ound l tmd eyocbjdr wmcem efb hd cbserchdj cb f spmdrd l rfjcus 54 cs 477pen5. YE.H.U.D. 8774^
V.58 Kcvdb tmd sun l tmd pdrcndtdrs `l f squfrd fbj f ecreod pr`vd tmft tmd sun l tmdcr frdf cs odfst wmdb tmd
scjd l tmd squfrd cs dqufo t` tmd jcfndtdr l tmd ecreod. YE.H.U.D. 877 q+ scb q, y > 6 + e`s qft q>:
p.
YE.H.U.D. 877 x8 4x + < ft tmd p`cbt W(8, 7) fbj V(5, 7) frd ft tmd rckmt fbkods
t` dfem tmdr. YE.H.U.D. 877 6. YE.H.U.D. 877
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8/10/2019 8_Applications of derivatives.pdf
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V.:4 Um`w tmft tmd mdckmt l tmd eyocbjdr l nfxcnun v ound tmft efb hd cbserchdj cb f e`bd l mdckmt m cs5
6m.
YE.H.U.D. 877=^
V.:< Zmd odbktm x l f rdetfbkod cs jderdfscbk ft tmd rftd l 4 en/ncbutd fbj tmd wcjtm y cs cberdfscbk ft tmd rftd
`l : en/ncbutd. [mdb x > = en fbj y > < en, lcbj tmd rftd l emfbkd l (f) tmd pdrcndtdr, (h) tmd frdf
`l tmd rdetfbkod. YE.H.U.D. 8773^
V.:; Lcbj tmd cbtdrvfos cb wmcem tmd lubetc`b l kcvdb hy l(x) > scb x + e`s x, 7 x8p,cs strcetoy cberdfscbk r strcetoy jderdfscbk. YE.H.U.D. 8773^
V.:= Cl tmd sun l tmd odbktms l tmd myp`tdbusd fbj f scjd `l f rckmt-fbkodj trcfbkod cs kcvdb, sm`w tmft tmd frdf
`l tmd trcfbkod cs nfxcnun wmdb tmd fbkod hdtwddb tmdn cs5
p. YE.H.U.D. 8773^
V.:3 F nfbulfeturdr efb sdoo x ctdns ft f prced l Xs
-
677
x4 dfem. Zmd e`st prced l x ctdns cs Xs
+677
4
x.
Lcbj tmd bunhdr l ctdns md sm`uoj sdoo t` dfrb nfxcnun pr`lct. YE.H.U.D. 8773^
V.47 Lcbj tmd dquftc`b l tmd tfbkdbt t` tmd eurvd y > 8x5 - wmcem cs pfrfoodo t` tmd ocbd :x 8y + 4 > 7.
YE.H.U.D. 8773^
V.46 Lcbj tmd cbtdrvfos cb wmcem tmd lubetc`b l kcvdb hy l(x) > x5+ 5x
6, x 7 cs YE.H.U.D. 8773^
(c) cberdfscbk (cc) jderdfscbk.
V.48 Lcbj tmd v`ound tmd ofrkdst eyocbjdr tmft efb hd cbserchdj cb f spmdrd l rfjcus r.
YE.H.U.D. 8773^
V.45 F tfbi wctm rdetfbkuofr hfsd fbj rdetfbkuofr scjds, pdb ft tmd t`p cs t` hd e`bstreutdj s` tmft cts jdptm
cs 8 n fbj v ound cs = n5. Cl hucojcbk l tfbi e`sts Xs ;7 pdr sq. ndtrd l`r tmd hfsd fbj Xs :4 pdr sq.
ndtrd l`r scjds, wmft cs tmd e`st `l odfst dxpdbscvd tfbi 0 YE.H.U.D. 8773^
V.4: Um`w tmft tmd v`ound l tmd krdftdst eyocbjdr tmft efb hd cbserchdj cb f e`bd l mdckmt m fbj sdnc-
vdrtcefo fbkod f cs8;
:p m5tfb8f. YE.H.U.D. 8767^
V.44 Lcbj tmd cbtdrvfos cb wmcem tmd l oo wcbk lubetc b cs YE.H.U.D. 8767^
(f) strcetoy cberdfscbk, (h) strcetoy jderdfscbk. YH`bus nfris^
V.4< Wr`vd tmft y >)e`s8(
scb:
q+q
qcs fb cberdfscbk lubetc`b cb
p8
,7 . YE.H.U.D. 8766^
V.4; Cl tmd rfjcus l f spmdrd cs ndfsurdj fs 3 en wctm fb drr`r l 7.75 en, tmdb lcbj tmd fppr`xcnftd drr`r
cb efoeuoftcbk cts surlfed frdf. YE.H.U.D. 8766^
V.4= Um`w tmft tmd rckmt-ecreuofr e`bd l odfst eurvdj surlfed fbj kcvdb v`ound mfs fb fotctujd dqufo t` 8
tcnds tmd rfjcus l tmd hfsd. YE.H.U.D. 8766^
V.43 F wcbj`w mfs tmd smfpd l f rdetfbkod surn`ubtdj hy fb dqucoftdrfo trcfbkod. Cl tmd pdrcndtdr l tmd
wcbj`w cs 68 n, lcbj tmd jcndbsc`bs l tmd rdetfbkod tmft wcoo pr`jued tmd ofrkdst frdf l tmd wcbj`w.
YE.H.U.D. 8766^
V.
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8/10/2019 8_Applications of derivatives.pdf
15/15
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