$\left(-3\right)\cdot\left(-15\right)$

$\left(23\right)-25-16\left(-2\right)-10$

$\left(4a^2b^4\right)\left(\frac{-a^3}{2b}\right)$

$\left(13m-5\right)\left(13m+5\right)$

$f\left(x\right)=\:\left(x-1\right)^2+2$

$2\left(3\times\frac{6}{9}+25\right)$

$x^2siny\:dx+\sqrt{9-x^2}dy=0$