# Help me proove the formula please

### Help me proove the formula please

Hey can someone help me please with the derivative dg/dr and how to proove tha formula?

If f(x,y,z)=g(r) and r=(x^2+y^2+z^2)^(1/2) proove that Δf=d^2g/dr^2 + (2/r)*dg/dr?

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