$4b^2-100$

$\left(\frac{1}{cot\left(x\right)}-1\right)\left(\frac{1}{cot\left(x\right)}+1\right)=2\tan\left(x\right)-sec^2x$

$\frac{12x^2-17x-40}{4x+5}$

$\left(3x-11yz\right)^2$

$\int\frac{x+4}{x^2+6x+19}dx$

$dx\:+\:\cot\left(y\right)\cdot dy\:=\:x^2\cdot\:\cot\left(y\right)\:\cdot dy$

$9x-7=-7$