$\left(x^3-7xy^2\right)^2$

$x^2+\frac{30}{4}x$

$1x.2x$

$\int\left(x^5+3x^3-2x\right)\sin\left(3x\right)dx$

$\frac{d}{dx}x^{cos\left(7x\right)}$

$\frac{1}{\frac{1}{\cos\left(x\right)}+\tan\left(x\right)}=\frac{1-\sin\left(x\right)}{\cos\left(x\right)}$

$\left(m+n+k\right)\left(m-n-k\right)$