distributive property of multiplication and the foil method
TRANSCRIPT
Multiplying BinomialsDistributive Property of Multiplication and
the FOIL Method
Primary Objective: To find the product of two binomials
Secondary Objective: To review the Distributive Property of Multiplication and to learn the FOIL Method.
Objectives
a(b+c) = a(b+c) = ab + acor
(b+c)a = (b+c)a = ba + ca
What property tell us that both results are the same (i.e. that ab + ac = ba + ca)?
The Commutative Property
Distributive Property of Multiplication (with respect to addition)
a(b-c) = a(b-c) = ab-acor
(b-c)a = (b-c)a = ba-ca
Again, per the Commutative Property, ab-ac = ba-ca
Distributive Property of Multiplication (with respect to subtraction)
(a+b)(c+d)
First distribute the multiplication of a to c and d , then distribute the multiplication of b to
c and d.
(a+b)(c+d) = ac + ad + bc + bd
The Distributive Property Works for Two Binomials
(a+b) (c+d) =
ac + ad + bc + bd First Outer Inner Last Terms Terms Terms Terms
This is called the FOIL Method
FOIL Method
Outer
Inner
First
Last
Learn the FOIL Methodbut remember that you are
using the
DISTRIBUTIVE PROPERTY
Example 1: Distributive Property of Multiplication (with respect to addition)
(2x+5)(3x+4)
(2x+5)(3x+4)
6x2 + 8x + 15x + 20 = First Outer Inner Last
combine like terms6x2 + 23x + 20
OuterInner
First Last
Example 2: Distributive Property of Multiplication (with respect to subtraction)
(3h+5)(3h-1)
(3h+5) (3h-1)
9h2 - 3h + 15h - 5 = First Outer Inner Last
combine like terms9h2 + 12h - 5
OuterInner
First Last
Your turn (with addition):
(n+7)(2n+5)
(n+7)(2n+5) =
2n2 + 5n + 14n + 35 =
2n2 + 19n + 35
Outer
Inner
First
Last
Your turn (with subtraction):
(z+4)(z-7)
(z+4) (z-7) =
z2 – 7z + 4z - 28 =
z2 - 3z – 28
Hint: draw line through “z” so you don’t confuse with “2”
Outer
Inner
First
Last