$\lim_{x\to-2}\left(\frac{x^4+5x+6}{x^4+5x-6}\right)$

$\log_b\left(\sqrt[4]{2b}\right)$

$5.5f-6c-7.4c+0.9f+6.35+c$

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

$\left(2x-1\right)\left(2x-5\right)$

$\left(\frac{\sin\left(x\right)}{\cos\left(x\right)}+\frac{\cos\left(x\right)}{\sin\left(x\right)}\right).\cos^2\left(x\right)$

$-618-9165-21$