Question

For what values of x is x2 + 2x = 24 true?

-6 and -4
-4 and 6
4 and -6
6 and 4

Answer 1

4 and -6.

Explanation:

x^2 + 2x = 24

When x = 4

4^2 + 2*4

= 16 + 8

= 24.

So it is true for x = 4.

When x = -6:

(-6)^2 + 2* -6

= 36 - 12

= 24.

So true for -6 also.