$$\lim_{x\to0}\left(1+sen\left(3x\right)\right)^{\frac{4}{x}}$$

$$5x+y=8$$

$$\frac{cos\left(x\right)}{1+cos\left(x\right)}-\frac{cos\left(x\right)}{1-cos\left(x\right)}=-2cot\left(x\right)^2$$

$$\lim_{x\to infinity}\left(x^2\cdot\:e^{\left(x\right)}\right)$$

$$30\:x\:+\:42\:y\:=\:66$$

$$\lim_{x\to\infty}\left(\frac{\sqrt{1-x}-3}{2+\sqrt[3]{x}}\right)$$

$$14+\left|23-\left(34-57\right)\right|$$