Objective 120
Multiplying 2 binomials,
(ax + b)(cx + d)
©2002 by R. Villar
All Rights Reserved
Multiplying 2 binomials, (ax + b)(cx + d)
We will use the FOIL method to multiply two binomials in
which the variables have coefficients other than one…
Example: Multiply (5x – 8)(2x – 4)
First
10x2
Outer
Inner
– 20x – 16x
Last
+ 32
Now, combine like terms...
10x2 – 36x + 32
Example: Multiply (4u + 9)(5u – 8)
First
Outer
Inner
Last
20u2 – 32u
+ 45u
– 72
Combine like terms...
20u2 + 13u – 72
Example: Multiply (8x2 + 3)(8x2 – 4)
First Outer Inner
64x4 – 32x2 + 24x2
Combine like terms...
64x4 – 8x2 – 12
Last
– 12
Example: Find the area of the rectangle
6x + 9
x–1
To find the area of a rectangle, multiply the length by the width...
(6x + 9)(x – 1)
First
6x2
Outer Inner
– 6x + 9x
Combine like terms...
6x2 + 3x – 9
Last
–9