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Quotient rule with exponential and power function

Let f(x)=exx2f(x) = \dfrac{e^x}{x^2}. Find f′(x)f'(x).

Hint

Use the quotient rule (fg)′=f′g−fg′g2\left(\dfrac{f}{g}\right)' = \dfrac{f'g - fg'}{g^2} with f(x)=exf(x) = e^x and g(x)=x2g(x) = x^2. Recall that ddx[ex]=ex\dfrac{d}{dx}[e^x] = e^x and ddx[x2]=2x\dfrac{d}{dx}[x^2] = 2x.

Step-by-step solution

Identify the numerator and denominator: let u=exu = e^x so u′=exu' = e^x, and let v=x2v = x^2 so v′=2xv' = 2x. Apply the quotient rule formula u′v−uv′v2\dfrac{u'v - uv'}{v^2} to get f′(x)=ex⋅x2−ex⋅2x(x2)2f'(x) = \dfrac{e^x \cdot x^2 - e^x \cdot 2x}{(x^2)^2}.

Simplify the numerator by factoring out ex⋅xe^x \cdot x: the numerator becomes exx(x−2)e^x x (x - 2), and the denominator is x4x^4. Canceling one factor of xx gives f′(x)=ex(x−2)x3f'(x) = \dfrac{e^x(x-2)}{x^3}.

Common factor in the quotient rule simplification

Hint
Step-by-step solution

The common factor canceled from both numerator and denominator was x. In the numerator e^x·x·(x-2), one factor of x was canceled with one factor of x from the denominator x⁴, leaving e^x(x-2) in the numerator and x³ in the denominator.

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