$Y= \sqrt{({2x^3+8 })^5} = (2x^3+8)^{\frac{5}{2} }$
ให้ $ U = (2x^3+8)$
$ Y = U^{\frac{5}{2} }$
$\frac{\partial Y}{\partial x} = \frac{\partial Y}{\partial U} \frac{\partial U}{\partial x}$
$\frac{\partial Y}{\partial x} = \frac{\partial U^{\frac{5}{2} }}{\partial U} \frac{\partial (2x^3+8)}{\partial x}$
$\frac{\partial Y}{\partial x} = \frac{5}{2}U^{\frac{3}{2} } (6 x^2)$
$\frac{\partial Y}{\partial x} = \frac{5}{2}(2x^3+8)^{\frac{3}{2} } (6 x^2)$
$\frac{\partial Y}{\partial x} = (15 x^2) \sqrt{(2x^3+8)^3} $
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