Im Really Sorry Bobak...
Im Just Asking To Check If Im Right...
btw you can check if your answer is right by putting a value to the variable
ex. $\displaystyle (x - 5)(x + 2)$ = $\displaystyle x^2 - 3x - 10$
so let x be uhm... 1
$\displaystyle (1 - 5)(1 + 2)$ = $\displaystyle 1^2 - 3(1) - 10$
$\displaystyle (-4)(3)$ = $\displaystyle 1 - 3 - 10$
$\displaystyle -12$ = $\displaystyle -12$
therefore our answer is correct