$42-3s=4s$

$\left(2-\sqrt{3}\right)\left(2+\sqrt{3}\right)$

$\int\frac{1}{\left(x^2-225\right)^{\frac{3}{2}}}dx$

$\left(2m^2-3m-14\right)^2$

$\int5x^2\left(1+2x^3\right)^5dx$

$\left(2x^2-7x-4\right)\left(x-4\right)$

$\left(-7x^4+7x^2+6x-8\right)-\left(9x^2-9+3x^5\right)$