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I need to check my answer on this practice problem

Solve for x in the equation
x^2 -7x-8=0
A. (-1,-8)
B. (1,-8)
C. (-1,8)
D. (1,8)
I think the answer is C.

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Krystal S. | The Math Magician The Math Magician
5.0 5.0 (10 lesson ratings) (10)
 x2 - 7x - 8 =0 

To solve for this you want two factors of 8 that when added together is -7 and when multiplied is -8. 

Given the multiple choice we know the correct factors are 1  and 8. We also know that one of the terms must be negative, that way you'll have to numbers that multiply to -8.

So it's either -1 and 8 or 1 and -8.  Since 1 + -8 = -7, We know that the correct choice is 1, -8 or B. 


Thank you Krystal so much. I realize I skipped a step now. I am cramming for a final in two weeks and was pretty confused on this one.