Math Problem Statement

以下の関数をxについて微分しなさい。 1. y = 2x^3 - 3x + 1 2. y = 1/x 3. y = 3/x^2 4. y = 1/x + 2/x^3

Solution

The question asks to differentiate each function with respect to xx. Let’s go through each of the four cases step by step:

1. y=2x33x+1y = 2x^3 - 3x + 1

Using basic differentiation rules: dydx=ddx(2x3)ddx(3x)+ddx(1)\frac{dy}{dx} = \frac{d}{dx}(2x^3) - \frac{d}{dx}(3x) + \frac{d}{dx}(1) dydx=6x23+0\frac{dy}{dx} = 6x^2 - 3 + 0 dydx=6x23\boxed{\frac{dy}{dx} = 6x^2 - 3}


2. y=1xy = \frac{1}{x}

Rewrite 1x\frac{1}{x} as x1x^{-1}, then differentiate: dydx=ddx(x1)\frac{dy}{dx} = \frac{d}{dx}(x^{-1}) dydx=x2\frac{dy}{dx} = -x^{-2} dydx=1x2\boxed{\frac{dy}{dx} = -\frac{1}{x^2}}


3. y=3x2y = \frac{3}{x^2}

Rewrite 3x2\frac{3}{x^2} as 3x23x^{-2}, then differentiate: dydx=ddx(3x2)\frac{dy}{dx} = \frac{d}{dx}(3x^{-2}) dydx=3(2)x3\frac{dy}{dx} = 3(-2)x^{-3} dydx=6x3\frac{dy}{dx} = -\frac{6}{x^3} dydx=6x3\boxed{\frac{dy}{dx} = -\frac{6}{x^3}}


4. y=1x+2x3y = \frac{1}{x} + \frac{2}{x^3}

Rewrite the terms as y=x1+2x3y = x^{-1} + 2x^{-3}, then differentiate term by term: dydx=ddx(x1)+ddx(2x3)\frac{dy}{dx} = \frac{d}{dx}(x^{-1}) + \frac{d}{dx}(2x^{-3}) dydx=x2+2(3)x4\frac{dy}{dx} = -x^{-2} + 2(-3)x^{-4} dydx=1x26x4\frac{dy}{dx} = -\frac{1}{x^2} - \frac{6}{x^4} dydx=1x26x4\boxed{\frac{dy}{dx} = -\frac{1}{x^2} - \frac{6}{x^4}}


Final Results:

  1. dydx=6x23\frac{dy}{dx} = 6x^2 - 3
  2. dydx=1x2\frac{dy}{dx} = -\frac{1}{x^2}
  3. dydx=6x3\frac{dy}{dx} = -\frac{6}{x^3}
  4. dydx=1x26x4\frac{dy}{dx} = -\frac{1}{x^2} - \frac{6}{x^4}

Would you like further clarification or examples?


5 Related Questions:

  1. How do you apply the power rule in differentiation?
  2. What are the general rules for differentiating polynomial functions?
  3. How does the chain rule apply to more complex functions?
  4. Can you explain higher-order derivatives of these functions?
  5. How do we find critical points using derivatives?

Tip:

Always rewrite terms like 1xn\frac{1}{x^n} as xnx^{-n} before differentiating—it simplifies the process!

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Math Problem Analysis

Mathematical Concepts

Differentiation
Power Rule
Derivative of Polynomial Functions
Derivative of Rational Functions

Formulas

Power Rule: d/dx[x^n] = nx^(n-1)
Derivative of a constant = 0
d/dx[1/x] = -1/x^2

Theorems

Basic Differentiation Rules
Rules of Rational Function Differentiation

Suitable Grade Level

Grades 10-12