$$\int_1^{\infty}\left(\frac{7}{x^2}\right)dx$$

$$6\:-\:2\left(2x\:+\:5\right)$$

$$\frac{d}{dx}4x^2+9y=36$$

$$\left(x-a\right)\left(x+b\right)$$

$$\sin^2x-3\sin x-4=0$$

$$10x^2+25x+5$$

$$\frac{9x^3-12x^4+21x^2+3}{3x}$$