$-71a-84b+50a+84b-45a+18a$

$49g^2\:+\:56gh\:+\:16h^2$

$-3a^2b+5a-6a^2b+18$

$\int_1^{\infty}\left(\frac{x^2+5x}{\left(1+x^2\right)^2}\right)dx$

$\lim_{x\to\infty}\frac{x^2+2}{2x^2+1}^{x^2}$

$\left(a-3\right)-\left(3-a\right)+\left(a-3\right)^{3}$

$\frac{dy}{dx}=\left(6x^3-3x^2+30x-15\right)$