$$1+2+3+4+5+6$$

$$\left(-2x-7+6x^4-1x^2\right):\left(x-4\right)$$

$$\int\left(16+x^2\right)^{-4}dx$$

$$8\sin\left(x\right)-4=0$$

$$\frac{d}{dx}x^3y^2-3x^4=8+y$$

$$y^2+6xy+9x^2$$

$$2cos\left(x\right)=-1$$