Question

Simplify: (k + 4)(2k + 5)=

Answer 1

2k2-22k+20

2k2+9k+20

2k2+13k+20

None of the above

Answer 2

FOIL
First: k*2k=2k^2
Outer: 5*k
Inner: 4*2k
Last:4*5
These are all added.

Answer 3

huh?

Answer 4

Have you ever heard of FOIL?

Answer 5

So, first off, since you have two positive numbers, it can't be 2k^2 - 22k + 20.

(k + 4)(2k + 5)
Going off of what rickjbr explained earlier:
- First (meaning the first two terms in each group): k x 2k = 2k^2
- Outer (meaning the first term in the first group and the last term of the second group):
k x 5 = 5k
- Inner (meaning the second term of the first group and the first term of the second group):
4 x 2k = 8k
- Last (meaning the last two terms of each group): 4 x 5 = 20

In total: 2k^2 + 5k + 8k +20
Now just add together the like terms!

This website does a good job of explaining the FOIL method way better than I ever could:
http://www.algebrahelp.com/lessons/simplifying/foilmethod/pg2.htm

I hope this helps! :D