SOLUTION: 7(x^2+8)-(2-4) ----------- ------- 16(x)+8 X= -2 I know I have to plug in -2 to X. However after that I'm not sure whether I have to distribute the 7 and the -1 or if I subtra

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: 7(x^2+8)-(2-4) ----------- ------- 16(x)+8 X= -2 I know I have to plug in -2 to X. However after that I'm not sure whether I have to distribute the 7 and the -1 or if I subtra      Log On


   

Question 775371: 7(x^2+8)-(2-4)
-------------------
16(x)+8
X= -2
I know I have to plug in -2 to X. However after that I'm not sure whether I have to distribute the 7 and the -1 or if I subtract them first and then distribute the result
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
7(x^2+8)-(2-4)
-------------------
16(x)+8
%287%28x%5E2%2B8%29-%282-4%29%29%2F%2816%28x%29%2B8%29

If you distribute the -1, considering it as

%287%28x%5E2%2B8%29-1%282-4%29%29%2F%2816%28x%29%2B8%29

you get:

%287%28x%5E2%2B8%29-2%2B4%29%2F%2816%28x%29%2B8%29

or

%287%28x%5E2%2B8%29%2B2%29%2F%2816%28x%29%2B8%29

If you subtract them first, you get

%287%28x%5E2%2B8%29-%28-2%29%29%2F%2816%28x%29%2B8%29

%287%28x%5E2%2B8%29%2B2%29%2F%2816%28x%29%2B8%29

So it doesn't matter which you do.  However
when you can combine the terms inside the
parentheses, that is always shorter.
The only time you MUST distribute is when 
a parentheses contains unlike terms, like
the first parentheses.

You must distribute the 7:

%287x%5E2%2B56%2B2%29%2F%2816%28x%29%2B8%29

And then combine like terms:

%287x%5E2%2B58%29%2F%2816%28x%29%2B8%29

Now plug in -2 for x

%287%28-2%29%5E2%2B58%29%2F%2816%28-2%29%2B8%29

%287%284%29%2B58%29%2F%28-32%2B8%29

%2828%2B58%29%2F%28-24%29

86%2F%28-24%29

-86%2F24

Divide top and bottom by 2

-43%2F12

Edwin