$\left(a^2-x\right)^3$

$\int4x^6dx$

$\int_1^2\left(x^2\right)-\left(x+3\right)dx$

$\int\frac{x^2\:-x\:+\:18}{x^3+3x}dx$

$\left(xy-4x\right)dx=-\left(x^2y+y\right)dy$

$\left(144y+100x\right)\left(144y-100x\right)$

$\lim_{x\to1}\left(\cos\frac{x\:\ln\left(x\right)}{x^2-1}\right)^x$