$$\frac{d}{dx}\:x^3-x^2-2x$$

$$3xdx=4ydy$$

$$\int\:\frac{4x^2+3x+7}{\left(x+1\right)\left(x^2+1\right)}dx$$

$$\frac{\sec\left(a\right)}{\csc\left(a\right)}$$

$$-12\left\{-7+\left[-4\left(-2+3\right)-\left(-10-2\right)\right]\right\}$$

$$\frac{3x^4}{9x^5}$$

$$\left(1+x^2\right)dy=\left(x-2xy\right)dx$$