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Product rule with a power function and an exponential

Let f(x)=x3exf(x) = x^3 e^x. Find f′(x)f'(x).

Hint

Write f(x)=u(x)v(x)f(x) = u(x)v(x) with u(x)=x3u(x) = x^3 and v(x)=exv(x) = e^x, then apply the product rule f′=u′v+uv′f' = u'v + uv'. Recall that ddx[x3]=3x2\frac{d}{dx}[x^3] = 3x^2 and ddx[ex]=ex\frac{d}{dx}[e^x] = e^x.

Step-by-step solution

Identify the two factors being multiplied: u(x)=x3u(x) = x^3 and v(x)=exv(x) = e^x. Their derivatives are u′(x)=3x2u'(x) = 3x^2 and v′(x)=exv'(x) = e^x, using the power rule and the fact that exe^x is its own derivative.

Apply the product rule f′(x)=u′(x)v(x)+u(x)v′(x)f'(x) = u'(x)v(x) + u(x)v'(x) to get f′(x)=3x2ex+x3exf'(x) = 3x^2 e^x + x^3 e^x. Factoring out the common term x2exx^2 e^x gives the simplified form f′(x)=x2ex(3+x)f'(x) = x^2 e^x(3 + x).

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