How do you differentiate f(x) =x sqrt(4-x^2)  using the product rule?

$- {x}^{2} / \sqrt{4 - {x}^{2}} + \sqrt{4 - {x}^{2}}$
d/dx(xsqrt(4-x^2) )=xd/dx(sqrt(4-x^2 ))+d/dx(x)sqrt(4-x^2)=x(1/2(4-x^2)^(-1/2)(-2x)+1sqrt(4-x^2)=-x^2/sqrt(4-x^2)+sqrt(4-x^2)
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