$15 ( 5 x + 4 ) ^ { 2 }$

$\frac{6^7}{6^3}$

$sec\left(-\pi\right)+csc\left(-\frac{\pi}{2}\right)$

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

$\left(x+3\right)^2\le10x+6$

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

$\frac{7a^4b^2+14ab-21a^2b}{7ab}$