The difference between the square of a negative number and five times the number is 40 more than the number. The number is? I think I set this up right, but how do I solve it ? (x)^2-5x=x+40 Beginning and Intermediate Algebra, Martin-Gay 5th Ed. Chapter 11

Expert Answers

An illustration of the letter 'A' in a speech bubbles

Let x be the unknown number.

Then `x^2-5x=40+x`

`x^2-6x-40=0`

`(x-10)(x+4)=0`

So by the zero product property either x=10 or x=-4.

Since we are asked for a negative number, x=-4.

-----------------------------------------------------------------

The number is -4

----------------------------------------------------------------

Approved by eNotes Editorial Team