Is the following identity true?

(x - 1) (x + 2) = x^2 + x - 2

Yes

Step-by-step explanation:

Lets do math:

(x-1) (x+2) is what we need to solve

x^2+2x-x-2 is what we get if we expand the equation

simplified version of that would be

x^2+x-2

which is equivalent to what was written in the beginning.

So yes the equation is correct