$2.5\:\cdot\:-3\frac{4}{5}$

$\lim_{x\to+\infty}\left(\frac{3x+1}{\sqrt{9x^2+1}}\right)$

$\int\sin^2\left(5x\right)cos^4\left(5x\right)dx$

$\int\frac{\ln\left(x\right)}{7x^{\frac{4}{3}}}dx$

$\frac{1}{4}x^2y^2+\frac{7}{8}x+8x+8^4+\frac{3}{8}x^2y^2-9x$

$\lim_{x\to0}\left(1+\sin\left(2x\right)^{\frac{3}{x^2}}\right)$

$\left(5a\right)\left(7b\right)$