#### Question

# Math question! Please help!?

Given the expression (3S+4)(4S+5), explain in words the steps taken to completely simplify the expression.

#### Answer

(3S + 4)(4S + 5)

The method to expand is called the FOIL method. FOIL means First, Outer, Inner, Last.

When multiplying two binomials (look up this word in your textbook, you know, that thing that is holding open your door).

In this example First is 3S×4S

Outer is 3S×5

Inner is 4×4S

Last is 4×5

So (3S + 4)(4S + 5) = 3S×4S + 3S×5 + 4×4S + 4×5

= 12S2 + 12S + 15S + 20 = 12S2 + 27S + 20

Your textbook has all of this in it. You must read it, I do not think you did.

3s+4x4s+5

-3 -3

s+4x4s+2

4x4=16

s+16s+2

-2 -2

s+14s

-s

s=13

(3S + 4)(4S + 5)

= 3S(4S + 5) + 4(4S + 5)

= 12S^2 + 15S + 16S + 20

= 12S^2 + 31S + 20

Steven is right. That's exactly how you do it. Take 3S x 4S, which = 12S(squared) or 12S^2. Then, you take 3S x 5 = 15S. Then, 4 x 4S = 16S. And finally, 4 x 5 = 20.

ANSWER: 12S^2 + 31S + 20

use the FOIL method

First

Outer

Inner

Last

F=(3S)(4S)

O=3S*5

I=4S*4

L=4*5

12S^2 +15S+16S+20

12S^2+31S+20