$$15.5-6.75$$

$$x^2+11x+30$$

$$\frac{2}{\sqrt{3}}x^{\frac{3}{2}}-\frac{4}{3}x^{\frac{3}{2}}+\frac{2}{3\sqrt{3}}x^{\frac{3}{2}}+c$$

$$\left(3\sqrt{x}+7\right)x^2$$

$$\left(\cot^2a+1\right)\left(\cot^2a-1\right)=\csc^4a-2\csc^2a$$

$$\left(t+9\right)^2=-3$$