$$\left(6x+\:8y\right)\left(13x+3y\right)$$

$$\lim_{x\to\infty}\left(\frac{lnx}{x}\right)$$

$$\int\frac{\left(2x-1\right)}{x^2+2x+3}dx$$

$$4\infty4$$

$$\pi\int_0^{\pi}\left(-\cos\left(x\right)^2\right)dx$$

$$\int x\left(x^2-25\right)^5dx$$

$$\int_{x^3}^1dx$$