Question 37461
From (x+1)(x-2) = 0, we can reason it this way:
We have two quantities being multiplied.
Their product is zero.
The ONLY way this can be is if one or both quantities are zero.
Thus we set each equal to zero, and find what values of x make them so.
So we have
x + 1 = 0 and then x = -1  and
x - 2 = 0 and then x = 2
and we're done.