$$6x+3x\left(4x+2\right)$$

$$\int\cos\left(7t\right)\cos\left(5t\right)dt$$

$$\int\left[6x^2\left(2x^3+7\right)^9\right]dx$$

$$x^2+15x+27=2x^2+24x+41$$

$$\left(z+9\right)\left(z-2\right)$$

$$\left(2xy^2+ye^x\right)dx+\left(2x^2y+e^x-1\right)dy=0$$

$$x'=x\cdot t$$