[Algebra]
Problem: Let $T=2$. Compute the product of $-T-i$ and $i-T$, where $i=\sqrt{-1}$.

Solution: Multiplying, $(-T-i)(i-T)=-(i+T)(i-T)=-\left(i^{2}-T^{2}\right)=1+T^{2}$. With $T=2,1+T^{2}=\mathbf{5}$.

Final answer: 5