$$7d+4d$$

$$\int\cot^2\left(x\right)\sec^4\left(x\right)dx$$

$$9+7r+17r+7\:para\:r\:9$$

$$x^4-16y^6$$

$$\int\frac{1}{\sqrt{4x^2+16x-20}}dx$$

$$x\frac{dy}{dx}+y=xcos\left(2x\right)$$

$$\left(11a^2b^3+3ab\right)^2$$