SOLUTION: How do I multiply (x - 10) (x+9)? I'm lost with how to figure these out. Thank you.

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Question 90298: How do I multiply (x - 10) (x+9)?
I'm lost with how to figure these out. Thank you.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Start with the given expression

%28x-10%29%28x%2B9%29

In order to multiply this, we need to FOIL the two parenthesis

When you FOIL, you multiply the terms in this order:
F-First (i.e. you multiply the first terms in each parenthesis which in this case are x and x)
O-Outer (i.e. you multiply the outer terms in each parenthesis which in this case are x and -10)
I-Inner (i.e. you multiply the inner terms in each parenthesis which in this case are -10 and x)
L-Last (i.e. you multiply the last terms in each parenthesis which in this case are -10 and -10)


So lets multiply the first terms:
x%2Ax=x%5E2 multiply x and x to get x%5E2



So lets multiply the outer terms:
x%2A9=9x multiply x and 9 to get 9x



So lets multiply the inner terms:
-10%2Ax=-10x multiply -10 and x to get -10x



So lets multiply the last terms:
-10%2A9=-90 multiply -10 and 9 to get -90

Now lets put all the multiplied terms together
x%5E2%2B9x-10x-90

Now combine like terms

x%5E2-x-90

So the expression

%28x-10%29%28x%2B9%29

FOILs to:

x%5E2-x-90