$\sec\left(x\right)+\csc\left(x\right)=\frac{1+\tan\left(x\right)^2}{\tan\left(x\right)\cdot\sin\left(x\right)}$

$7mn\frac{7x}{3}-1$

$3xy+z\:\:\:x=2$

$\left(xy+x^2\right)dx-x^2dy$

$\tan\left(x\right)\cdot\csc\left(x\right)\cdot\sec^2\left(x\right)\cdot\cos\left(x\right)=\sec^2\left(x\right)$

$\int3xcos^3\left(x^2+2\right)dx$

$6z=x-3z$