$\left[\left(a+b\right)+\left(xy\right)\right]\left[\left(a+b\right)-\left(x-y\right)\right]$

$\left(6+9\right)\cdot\left(-5-4\cdot\left(3+\left(-2\right)\right)\right)$

$\left(5c+8\right)\left(3c-1\right)$

$\frac{d}{dx}x^2y=cos\left(y\right)$

$x^3+y^3=28$

$\sqrt{3}\sec\left(3x\right)=2$

$\left(7b^2-8d^3\right)^2$