+311 Let $a$ and $b$ be real numbers such that $a+b=-1$. Compute $a^2-b^2+a-b$.
+311 Nvm, I found out.
$a^2-b^2$ factorizes as $(a-b)(a+b)$. So the full expression factorizes as$$(a-b)(a+b)+(a-b)=(a-b)(a+b+1)$$Since $a+b=-1$, we have that $a+b+1=0$. So the product is $0$. 
