$\frac{\sec\left(x\right)}{\sin\left(x\right)}=\sec\left(x\right)\csc\left(x\right)$

$-45b^2-30ab-5a^2$

$-\left(4889\right)-\left(-20\right)$

$\left(987.654\right)x\left(-987\right)=\:$

$\int e^{-9x}dx$

$\lim_{h\to0}\left(\frac{\left(y\left(x+h\right)-y\left(x\right)\right)}{h}\right)$

$\left(1+x\right)\frac{dy}{dx}-2y=1$