$3a+21$

$\int\left(\frac{x^2}{\left(15+6x-9x^2\right)^2}\right)dx$

$-4\sin^2\left(x\right)+\sin\left(x\right)=0$

$\left(7+7c^2\right)\left(7-7c^2\right)$

$245a^5b^6-280a^4b^4+80a^3b^6$

$\lim_{x\to0}\left(\frac{3\sin\left(x\right)-3x}{2x^2}\right)$

$\frac{9x^2y^2}{18x^4}18x^4y$