Solve y/2*pi=r^3+3r^2

$$\frac{ y }{ 2 \times \pi } = { r }^{ 3 } +3 { r }^{ 2 }$$

Solve for y

$$y=2\pi \left(r+3\right)r^{2}$$

Steps for Solving Linear Equation

The equation is in standard form.

$$\frac{1}{2\pi }y=r^{3}+3r^{2}$$

Divide both sides by \frac{1}{2}\pi ^{-1}.

$$\frac{\frac{1}{2\pi }y\times 2\pi }{1}=\frac{\left(r+3\right)r^{2}\times 2\pi }{1}$$

Dividing by \frac{1}{2}\pi ^{-1} undoes the multiplication by \frac{1}{2}\pi ^{-1}.

$$y=\frac{\left(r+3\right)r^{2}\times 2\pi }{1}$$

Divide \left(3+r\right)r^{2} by \frac{1}{2}\pi ^{-1}.

$$y=2\pi \left(r+3\right)r^{2}$$