$9x^2+15x+4$

$2x^4-3x^3-9x^2+4$

$-1.2+3.4$

$\lim_{x\to\infty}\left(1+\frac{\left(8.2x^2+6.3x+5.6\right)}{\left(4.3x^2+4.8x+6.8\right)}\right)$

$10-28:\left(-7\right)\cdot\left(-2\right)+6$

$\frac{x^4-\:y^4}{x-y}$

$\int_{\frac{\pi}{2}}^{\frac{\pi}{2}}\frac{x^2\sin x}{1+x^6}dx$