$\frac{cos^3x}{1+sin\:x}=\frac{1-sin\:x}{sec\:x}$

$\int_0^{\frac{\pi}{2}}\left(\frac{9}{senx^2}\right)dx$

$\frac{3}{x}+3$

$10^2+100x+250$

$\left(3t\:+7\right)\:\left(3t\:+\:2\right)\:$

$\left[\left(-5\right)x\left(-2\right)+\left(+10\right)\right]:\left(-20\right)+\left(+78\right):\left(-2\right)$

$\left(9\right)\left(-4\right)\left(6\right)$