$13a+22b-81c-12x+4-\left(10a-20b+35c-2x+1\right)$

$\csc\left(x\right)=\sec^2\left(x\right)csc\left(x\right)-sec\left(x\right)tan\left(x\right)$

$\frac{12y^7}{2y^4}$

$\lim_{x\to0}\left(\frac{9-e^{2x}}{3-e^{x}}\right)$

$\frac{\sec a}{\tan a+\cot a}=\sin$

$3a^2-a^2$

$\frac{dy}{dx}=6x^3\left(5+y^2\right)^{\frac{3}{2}}$