$-7x^2+4x^2$

$\left(-2a^3b^{-1}\right)\left(5a^{-2}b^2\right)$

$\frac{\cos\left(\theta\right)}{\sec\left(\theta\right)}$

$\lim_{n\to1}\left(\frac{-2t}{\left(n-1\right)\left(n+1\right)\pi}\right)$

$\frac{x^3+x^2+x-2}{x-1}$

$x+5=-3x+25$