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

$x^2\left(4y-1\right)$

$2x^2+25\le75$

$\lim_{x\to0}\left(5sinx\right)^7tan\left(x\right)$

$\frac{x^2}{\left(1-x^2\right)}$

$\frac{dx}{dt}=\frac{1}{x-t}$

$\int e^{7x}\sec\left(e^{7x}\right)\tan\left(e^{7x}\right)dx$