$-15x-3y$

$\frac{d}{dx}\left(x^2+3x+y-1\right)$

$\frac{d}{dy}\left(z^3xy+yz-2=0\right)$

$4m^2-4m\left(1-a\right)+\left(1-a\right)^2$

$\frac{\cot\left(x\right)}{\cos\left(x\right)}+\:\frac{\sec\left(x\right)}{\cot\left(x\right)}$

$x^3\left(5-x\right)^2$

$\left(\:a^6+\:a^{-6}\:\right)^3$