$\cos\left(4x\right)x\cos\left(2x\right)+\sin\left(2x\right)x\sin\left(4x\right)$

$\left(y^2+1\right)\left(y^2-1\right)-\left(y^2+1\right)^2$

$\left(9a^6b^4+c^5\right)^3$

$\frac{d}{dx}\sqrt{y}+6xy=3$

$-7x^2y^2\left(8x^2y-5xy+11xy^2-31\right)$

$4x^4y^4-16x^2+16$

$\int_0^6\left(xe^{\left(-x\right)}\right)dx$