$$-8x\:-\:11x$$

$$\frac{d^2}{dx^2}\left(y+\sqrt{3x^2+1}\right)$$

$$\frac{8^4}{2^2}$$

$$15a^2-8ab+6a^2-6ab+9+4a^2-13ab$$

$$2mb-an+2mn-ab$$

$$\lim_{x\to\infty}\left(\frac{sin^2\left(2x\right)}{x}\right)$$

$$x-4x$$