$5-\left(3+4\right)-\left(6-5\right)$

$\frac{2\cos^2\left(x\right)}{\sin\left(x\right)}=2\cot\left(x\right)$

$\int\left(-35x+21\right)\tan\left(5x^2-6x\right)dx$

$\int_{-\infty}^0xe^x\:dx$

$\left(2z-4\right)\left(2z+9\right)$

$a^2-4a+64$

$2\left(-z+1\right)-3\left(1+z\right)<-3z+2$