$49x^4+16y^4-56x^2y^2-z^2$

$\int\:\frac{e^x-e^{3x}}{e^x-e^{2x}}dx$

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

$\frac{2x^2-10x}{2x^3-50x}$

$\frac{dy}{dx}+\cos\left(x\right)=2\cos\left(x\right)$

$4a^2b+6a^2b^4-2a^2$

$5\log\left(x\right)-5\log\left(x^2+1\right)+4\log\left(x-1\right)$