$\int\frac{cosx}{4sin^2\left(x\right)+5sin\left(x\right)+4}dx$

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

$\left(50-0.5x\right)\left(3000+60x\right)$

$\int2\sec^3\left(4x\right)\tan\left(4x\right)dx$

$\int e^{x-1}dx$

$2x+1=3x$

$3\left(3-3x\right)=2\left(x+3\right)-30$