\(10p^2 +20=1490\)
\(10p^2=1490-20\) \(Subtract \ 20 \ from \ both \ sides\)
\(10p^2=1470\)
\(p^2= \dfrac{1470}{10}\) \(Divide \ both \ sides \ by \ 10\)
\(p^2=147\)
\(p=+ \sqrt{147}\) \(Take \ the \ square \ root \ of \ both \ sides\)
\(p=+7 \sqrt{3}\)
