Which is a solution to the equation?
(x-2)(x + 5) = 18
x = -10
x = -7
o x = -4
x = -2

Explanation:

There are at least two ways to do this. Method 1 is to FOIL out the left hand side, then subtract 18 from both sides, and apply the quadratic formula or factor

(x-2)(x+5) = 18

x^2+5x-2x-10 = 18

x^2+3x-10 = 18

x^2+3x-10-18 = 0

x^2+3x-28 = 0

(x+7)(x-4) = 0

x+7 = 0 or x-4 = 0

x = -7 or x = 4

Method 2 is to go through each answer choice and plug those x values, one at a time, into the original equation. If you get the same number on both sides, then you found your answer.

So for instance, x = -10 does not work because

(x-2)*(x+5) = 18

(-10-2)*(-10+5) = 18 ... replace every x with -10

(-12)*(-5) = 18

60 = 18 this equation is false, so x = -10 is not a solution

But x = -7 works as method 1 shows above, and we can confirm it as such

(x-2)*(x+5) = 18

(-7-2)*(-7+5) = 18 ... x is replaced with -7

(-9)*(-2) = 18

18 = 18 true equation; confirms x = -7

You should find that choices C and D are similar to choice A, and they won't work.

For the sake of completeness, let's confirm x = 4 as well

(x-2)*(x+5) = 18

(4-2)*(4+5) = 18

(2)*(9) = 18

18 = 18

Both solutions found in method 1 have been confirmed.