$\frac{\tan\left(-x\right)}{\sec\left(x\right)}$

$-8\left(6x+4\right)$

$\lim_{x\to0}1+3x^{2x^{-1}}$

$-18x-123$

$\frac{\left(x+y\right)\left(x-y\right)}{\left(x+y\right)^2}$

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

$\cos^2x\sin^3\left(x\right)=\frac{1}{16}\left(\sin\left(3x\right)-\sin\left(5x\right)+2\sin\left(x\right)\right)$