factoring review eq: how do i factor polynomials?
TRANSCRIPT
Ex. 1) Factor x2 – 25
• This is a “Difference of Two Squares”• “difference” means subtraction• ALWAYS CHECK FOR A GCF FIRST!
• (x + 5)(x – 5) FOIL to confirm!
Ex. 2) Factor 4a2 – 25b2
• Are both of these terms perfect squares?• Is there a minus sign in the middle?• Then use “difference of squares”.
• (2a + 5b)(2a – 5b)• FOIL to confirm!
Ex. 3) Factor 9x2 – 15
• Are both of these perfect squares?• NO• 15 is not.• So , you can’t factor it using difference of
squares…• BUT you can factor using GCF.• 3(3x2 – 5)
Ex. 4) Factor 16r2 + 49
• Are both terms perfect squares?• Yes• Is there a minus sign in the middle?• NO!• Can’t factor using difference of squares.• Is there a GCF?• NO ….
• Must be PRIME
Ex. 5) Factor 25n2 – 100 • What should you always ask yourself FIRST???• GCF• 25 (n2 – 4)• 25(n + 2)(n – 2)• If you forgot, (5n + 10)(5n – 10) . . . • Both of these factors are not factored COMPLETELY b/c they
still have a common factor of 5 (each)! • MUST DO GCF FIRST!!!!!!!!!!!!
Ex. 6-7: Practice
Factor Completely!Ex. 6) X2 – 4Ex. 7) 36a2 – 49b2
6. (x + 2)(x – 2)7. (6a + 7b)(6a – 7b)
Perfect Square Trinomial
• x²+bx+c• What multiplies to give you “c” and adds
to give you “b”?• Your answer is a binomial squared
Ex. 8) Factor • x2 + 20x +100• (x + 10)(x + 10)• When both factors are the same, this is called a PERFECT
SQUARE TRINOMIAL and could be written…….
• (x + 10)2
Ex. 9) Factor completely.• x2 + 6x + 8• When factoring, always make sure your polynomial is in
standard form & always look for a GCF 1st.• Definition: leading coefficient
– Coefficient on the term with the highest degree in a polynomial. If written in standard form, it will lead out the problem.
• What multiplies to give you 8 AND adds to give you 6?• Answer: (x + 4) (x + 2)• Check yourself by FOIL.
Ex. 13) Factor 2x2 –18x + 40
• What do you do first?• Don’t forget you can ALWAYS use GCF first!
• 2(x – 4)(x – 5)• FOIL, then distribute the 2 to check yourself!
Ex. 14) Factor x2 + 2x - 8
• What multiplies to give you -8, and adds to be 2?• 4, -2• Which number goes where…. ?
• (x + 4)(x – 2) FOIL to check!
Do Now:
• Factor the following:1. x² - 362. 9x² - 643. x² - 18x + 814. x² + 7x + 105. 3x² + 16x + 166. 4x² - 32x + 64
Homework Answers:
4. 2x(x-4)5. 2y(y-3)6. 5ax(x-3a)10. (x+3)(x+2)11. (x+7)(x+1)12. (y-4)(y-1)13. (x+2)(x-6)14. (y+3)(y-12)15. (x+12)(x-2)
16. (2x+5)(x+2)17. (3x+2)(x+1)18. (5x-2)(x+3)22. (x²+9)(x+3)(x-3)23. 2(x+2)(x-2)24. (4x+5)(4x-5)25. (x+4)²30. 3(x+2)31. 3(x²+6)
Assignment
• Pg. 296, #’s40-57 ALL• #46 – REWRITE IT: x²-22x-48• #48 – Rewrite in standard form• #’s 49-51 – Rewrite, then factor out a negative:
-x²+10x+56 becomes –(x²-10x-56)