$\int3x\left(2x+1\right)^3dx$

$2\cos^2x-3\cos x+1=0$

$y'-\frac{y}{t}=y^{-1}$

$\left(-\frac{2x^4y}{5}+\frac{xy^2}{4}\right)^2$

$x^2-\left\{-7xy+\left[-y^2+\left(-x^2+3xy-2y^2\right)\right]\right\}$

$\left(5p-2\right)\left(5p+7\right)$

$\lim_{x\to\infty}\left(\frac{x+6}{x+1}\right)^{\left(x+4\right)}$