$f ( t ) = \frac { 9 - t ^ { 2 } } { t - 3 }$

$\frac{\left(tan\left(x\right)-sin\left(x\right)\right)}{2tan\left(x\right)}$

$6m^2+7m-20$

$\cos\left(y\right)\left(\tan\left(y\right)+\cot\left(y\right)\right)$

$11x+37y-4.4x-24.5y$

$-15\cdot56$

$\left(2^a-3\right)\left(2^a+8\right)$