$$\frac{-x^2+1}{x^2-4}$$

$$2\left(2r+3\right)+2\left(2r+5\right)$$

$$\int\sin^2\left(\frac{x}{2}\right)dx$$

$$3xy^2-5x^2y-8x^3-5x^2+8x^3-3xy^2$$

$$ln\sqrt[3]{x+3}$$

$$3a-12s+2a-4s$$

$$-7\left(1-p\right)-6\left(6p-5\right)$$