$\frac{1}{2cotx\left(1-cos^2x\right)}$

$g\left(x\right)=-\frac{1}{x^2}\:y\:f\left(x\right)=-x^4-4x^2$

$xy+yx$

$15abc-4ab^2c+\left(5a^2bc\right)-\left(-4ab^2c-6abc+6a^2bc\right)$

$\lim_{x\to-1}\left(\frac{5x^2-7x+2}{x+1}\right)$

$29+42+57+10$

$2\log\left(a^2b\right)=3+\log\left(a\right)-\log\left(b\right)$