$\int_0^7\left(xe^{-x}\right)dx$

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

$x^2\:+\:12x\:+27$

$\int\frac{12y^2}{4y^3+1}dx$

$6cos^2\left(x\right)+cos\left(x\right)-1$

$\int\left(3r^2\sqrt{1+r^3}\right)dr$

$\frac{3}{x}=\frac{2}{x+1}$