Math Problem Statement

Find f’(x) and f’’(x) for (e^x)/(x^2). Simplify and factorise your answers!

Solution

Let f(x)=exx2f(x) = \frac{e^x}{x^2}. We'll calculate f(x)f'(x) (first derivative) and f(x)f''(x) (second derivative), simplify, and factorize where possible.


Step 1: First Derivative f(x)f'(x)

Using the quotient rule, ddx(uv)=uvuvv2\frac{d}{dx} \left( \frac{u}{v} \right) = \frac{u'v - uv'}{v^2}, where:

  • u=exu = e^x, u=exu' = e^x,
  • v=x2v = x^2, v=2xv' = 2x,

we get: f(x)=ex(x2)ex(2x)x4f'(x) = \frac{e^x(x^2) - e^x(2x)}{x^4}

Simplify the numerator: f(x)=ex(x22x)x4f'(x) = \frac{e^x(x^2 - 2x)}{x^4}

Factorize the numerator: f(x)=exx(x2)x4f'(x) = \frac{e^x x(x - 2)}{x^4}

Simplify: f(x)=ex(x2)x3f'(x) = \frac{e^x(x - 2)}{x^3}


Step 2: Second Derivative f(x)f''(x)

Now differentiate f(x)=ex(x2)x3f'(x) = \frac{e^x(x - 2)}{x^3} again, using the quotient rule:

  • u=ex(x2)u = e^x(x - 2), u=ex(x2)+ex1=ex(x1)u' = e^x(x - 2) + e^x \cdot 1 = e^x(x - 1),
  • v=x3v = x^3, v=3x2v' = 3x^2,

f(x)=uvuvv2f''(x) = \frac{u'v - uv'}{v^2}

Substitute: f(x)=ex(x1)x3ex(x2)3x2x6f''(x) = \frac{e^x(x - 1)x^3 - e^x(x - 2)3x^2}{x^6}

Simplify the numerator: Numerator=ex(x1)x33ex(x2)x2\text{Numerator} = e^x(x - 1)x^3 - 3e^x(x - 2)x^2

Factorize exx2e^x x^2 from both terms: Numerator=exx2[x(x1)3(x2)]\text{Numerator} = e^x x^2 \left[ x(x - 1) - 3(x - 2) \right]

Simplify inside the brackets: x(x1)3(x2)=x2x3x+6=x24x+6x(x - 1) - 3(x - 2) = x^2 - x - 3x + 6 = x^2 - 4x + 6

Thus: Numerator=exx2(x24x+6)\text{Numerator} = e^x x^2 (x^2 - 4x + 6)

Simplify f(x)f''(x): f(x)=exx2(x24x+6)x6f''(x) = \frac{e^x x^2 (x^2 - 4x + 6)}{x^6}

Simplify further: f(x)=ex(x24x+6)x4f''(x) = \frac{e^x (x^2 - 4x + 6)}{x^4}


Final Results:

  1. First derivative: f(x)=ex(x2)x3f'(x) = \frac{e^x(x - 2)}{x^3}

  2. Second derivative: f(x)=ex(x24x+6)x4f''(x) = \frac{e^x(x^2 - 4x + 6)}{x^4}


Let me know if you have any questions! 😊 Here are 5 related practice problems:

  1. Differentiate f(x)=ln(x)x2f(x) = \frac{\ln(x)}{x^2}.
  2. Find f(x)f'(x) and f(x)f''(x) for f(x)=sin(x)x3f(x) = \frac{\sin(x)}{x^3}.
  3. Simplify and factorize ddx(e2xx2)\frac{d}{dx}\left(\frac{e^{2x}}{x^2}\right).
  4. Calculate the second derivative of g(x)=x2exg(x) = \frac{x^2}{e^x}.
  5. Solve for f(x)f'(x) and f(x)f''(x) for f(x)=1xnf(x) = \frac{1}{x^n}.

Tip: Always simplify the numerator step by step in the quotient rule; it avoids common errors!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Differentiation
Quotient Rule
Simplification
Factorization

Formulas

Quotient Rule: d/dx (u/v) = (u'v - uv')/v^2

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12