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Section 3.12 : Higher Order Derivatives

6. Determine the second derivative of \(g\left( x \right) = \sin \left( {2{x^3} - 9x} \right)\)

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Not much to this problem other than to take two derivatives so each step will show each successive derivative until we get to the second. The first derivative is then,

\[g'\left( x \right) = \left( {6{x^2} - 9} \right)\cos \left( {2{x^3} - 9x} \right)\] Show Step 2

Do not forget that often we will end up needing to do a product rule in the second derivative even though we did not need to do that in the first derivative. The second derivative is then,

\[\require{bbox} \bbox[2pt,border:1px solid black]{{g''\left( x \right) = 12x\cos \left( {2{x^3} - 9x} \right) - {{\left( {6{x^2} - 9} \right)}^2}\sin \left( {2{x^3} - 9x} \right)}}\]