$$3y\:+\:27y^2$$

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

$$cos\:x\:\left(tan\:x\:+cot\:x\:\right)=cos\:x$$

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

$$\int\left(\frac{1.9}{50+t}\right)dt$$

$$\int\frac{2}{\left(\sqrt{1-4x^2}\right)}dx$$

$$\left(cotx+\left(cos^2x+sin^2x\right)\right)\left(cotx-\left(cos^2x+sin^2x\right)\right)$$