SOLUTION: 8x^2-16x-120=0 Solve the equation for x.

Question 687574: 8x^2-16x-120=0 Solve the equation for x.
Answer by josh_jordan(263) (Show Source): You can put this solution on YOUR website!
Since each number in the equation is a multiple of 8, dividing the equation by 8 will make the equation easier to solve. After dividing everything by 8, you end up with:

Let's first try to solve for x by factoring. We need for the same two numbers that can be multiplied to give us -15, be added together to give us -2:

1 x -15 = -15; 1 + -15 = -14

-1 x 15 = -15; -1 + 15 = 14

-3 x 5 = -15; -3 + 5 = 2

3 x -5 = -15; 3 + -5 = -2 <----- THIS WORKS!

Now, we set up in factor form:

And put each set of parenthesis equal to zero, and solve for x:

=

=

Final Answer: x = -3, 5
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