$2x^2-21x+50$

$\left(-3x^2y-2xy^2-xy\right)\left(x^2-y+1\right)$

$5x-3x+8x+5$

$\int\frac{\left(sinx\right)}{\left(2-cosx\right)^2}dx$

$12a-8a+10a+3a-18a+5a$

$2x\cdot3ax$

$\sec\left(x\right)^2\left(8+3\csc\left(x\right)\right)+\tan\left(x\right)\left(-3\csc\left(x\right)\cot\left(x\right)\right)$