$\left(2800\right)\left(0.02\right)\left(4\right)$

$\lim\:_{x\to\:0}\left(\frac{\sqrt{49-x^2}-7}{x}\right)$

$\frac{25}{12}x-2x$

$\left(i^4-9k\right)^2$

$13\left(5\right)+13\left(2\right)$

$\left(\frac{-343}{216}\right)^{\frac{2}{3}}$

$\left(x^4y+3y^4\right)dx+\left(\frac{x^5}{5}+12xy^3\right)dy=0$