SOLUTION: Some students simplify, 2x^2-32/x-4 as 2x-8 and then it says choose values of x to show this is not true. Then simplify it correctly. I know this is probably so simple, but I'm

Algebra ->  Numeric Fractions Calculators, Lesson and Practice -> SOLUTION: Some students simplify, 2x^2-32/x-4 as 2x-8 and then it says choose values of x to show this is not true. Then simplify it correctly. I know this is probably so simple, but I'm       Log On


   

Question 7746: Some students simplify, 2x^2-32/x-4 as 2x-8 and then it says choose values of x to show this is not true. Then simplify it correctly.
I know this is probably so simple, but I'm stuck, help? :/
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
First, you ought to use parentheses around the numerator and denominator to make it absolutely clear.
(2x^2 - 32)/(x-4) If you were to perform the indicated division either by long division or by synthetic division, you would get a result of: 2x + 8.
I find it easier to factor the numerator and cancel like factors in the numerator and denominator.
%282x%5E2+-+32%29%2F%28x+-+4%29+=+2%28x+%2B+4%29%28x+-+4%29%2F%28x+-+4%29 Cancel the (x-4)'s
%282x%5E2+-+32%29%2F%28x+-+4%29+=+2%28x+%2B+4%29 Simplify.
%282x%5E2+-+32%29%2F%28x+-+4%29+=+2x+%2B+8
You can perform the suggested test on the erroneous answer (2x - 8) and on the correct solution (2x + 8) by substituting a convenient value for x in both cases.