$$\frac{x+2}{x^2+4x+4}:\:\frac{x^2+5x+6}{x+3}$$

$$6+5d+d^2$$

$$\frac{3}{1-\sin\left(a\right)}+\frac{3}{1+\sin\left(a\right)}$$

$$-6c-9c$$

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

$$\frac{\sec x^2-1}{\sin^2x}=\sec^2x$$