Exercise · ZW-PRODUCT-RULE-005 · ★★☆ Intermediate
Differentiate \(f(x)=\left(x^{2} + 1\right) \cos {x}\).
Choose one option.
Show answer
- C. \(2 x \cos {x} - \left(x^{2} + 1\right) \sin {x}\)
Explanation
With \(u=x^{2} + 1\) and \(v=\cos {x}\): \(u'=2 x\), \(v'=- \sin {x}\). Then \((uv)'=u'v+uv'=2 x \cos {x} - \left(x^{2} + 1\right) \sin {x}\).
Review the concept: Product rule
Rule giving the derivative of a product of two differentiable functions: \((fg)^{\prime}=f^{\prime}g+fg^{\prime}\). It is not the product of the derivatives.
\[(f\,g)'=f'\,g+f\,g'\]
More practice problems: product rule
- ZW-PRODUCT-RULE-001 What is the mistake in this statement? "(x^2sin x)'=2xcos x"
- ZW-PRODUCT-RULE-002 Differentiate f(x)=x^2 sin x.
- ZW-PRODUCT-RULE-003 Differentiate f(x)=(3 x + 1) e^x.
- ZW-PRODUCT-RULE-004 Differentiate f(x)=x ln (x ).
- ZW-PRODUCT-RULE-006 Differentiate f(x)=e^x sin x.
- ZW-PRODUCT-RULE-007 Differentiate f(x)=x^3 e^x.
- ZW-PRODUCT-RULE-008 Differentiate f(x)=(x + 2) cos x.
- ZW-PRODUCT-RULE-009 Differentiate f(x)=x sin x e^x by applying the product rule twice.