$\int_1^{\infty}\left(\frac{ln\left(15x\right)}{x^2}\right)dx$

$4ax-1^2$

$e^{-y}\frac{dy}{dx}=x+x^3$

$\left(\left(-x\right)^4\right)^5$

$\frac{\left(1-0.25\cdot\:\:x\right)^2}{\left(1-x\right)\cdot\:\left(1-0.5\cdot\:\:x\right)}$

$-12\left(-4\left(5-3\right)\right)-2\left(+23+21\right)$

$\lim_{x\to4}\left(\frac{\left(x^2-16\right)}{\ln\left(x-3\right)}\right)$