$$\frac{ex+f}{x^2-9}=\frac{a}{x+3}+\frac{b}{x-3}$$

$$a-4=8$$

$$2x+4=-x+19$$

$$\cot^2\left(b\right).\:\tan^2\left(b\right)+1=2$$

$$\int_{-1}^1\left(7x+8x\right)dx$$

$$2sin^2x=3sinx+2$$

$$\int x^2e^{-\frac{2r}{a}}dx$$