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Question

Find the derivation of f(x) = 1/x2

The correct answer is

-2/x3

Finding the derivative of a function is a fundamental concept in calculus. The question asks us to find the derivation of the function \(f(x) = \frac{1}{x^2}\). This involves applying the rules of differentiation, specifically the power rule, to determine the rate of change of the function.

Derivative of a Function: Understanding the Power Rule

To find the derivation of \(f(x) = \frac{1}{x^2}\), we first need to rewrite the function in a form that is easier to differentiate using the standard power rule. The power rule states that if \(f(x) = x^n\), then its derivative, denoted as \(f'(x)\) or \(\frac{d}{dx}f(x)\), is given by \(f'(x) = nx^{n-1}\).

  • Step 1: Rewrite the function in power form.

    The given function is \(f(x) = \frac{1}{x^2}\). Using the property of exponents that \(\frac{1}{a^n} = a^{-n}\), we can rewrite \(f(x)\) as:

    \(f(x) = x^{-2}\)

  • Step 2: Apply the power rule for differentiation.

    Now, we apply the power rule \(f'(x) = nx^{n-1}\) to \(f(x) = x^{-2}\). Here, \(n = -2\).

    \(f'(x) = (-2)x^{(-2)-1}\)

    \(f'(x) = -2x^{-3}\)

  • Step 3: Rewrite the result in positive exponent form.

    Finally, to express the derivation in a more conventional format, we convert the negative exponent back to a positive one using the same exponent property \(\frac{1}{a^n} = a^{-n}\):

    \(f'(x) = -\frac{2}{x^3}\)

Detailed Analysis of the Derivation

Let's summarize the derivation process for \(f(x) = \frac{1}{x^2}\):

  1. Start with the function: \(f(x) = \frac{1}{x^2}\)
  2. Convert to exponential form: \(f(x) = x^{-2}\)
  3. Apply the power rule \(\frac{d}{dx}(x^n) = nx^{n-1}\): \(\frac{d}{dx}(x^{-2}) = (-2)x^{-2-1}\)
  4. Simplify the exponent: \(= -2x^{-3}\)
  5. Convert back to fractional form: \(= -\frac{2}{x^3}\)

Therefore, the derivation of \(f(x) = \frac{1}{x^2}\) is \(-\frac{2}{x^3}\).

Comparing with Options

Let's look at the given options for the derivation:

  • Option 1: \(-2/x^3\) - This matches our calculated derivation.
  • Option 2: \(2/x^3\) - This is incorrect as the sign is positive. The power rule correctly yields a negative sign due to \(n = -2\).
  • Option 3: \(-1/2x\) - This is incorrect. It seems to imply an incorrect application of rules, possibly confusing differentiation with integration or applying a constant rule incorrectly.
  • Option 4: \(1/2x\) - This is incorrect for the same reasons as Option 3, plus the sign error.

Based on our step-by-step derivation using the power rule, the correct answer is \(-\frac{2}{x^3}\).

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Important Questions from Evaluation of derivatives

  1. Differentiate {-log (log x), x > 1} with respect to x

  2. The derivative of the function f(x) = -3x2 + 6x - 4 is given by:
  3. Differential coefficient of log10 x with respect to logx 10 is

  4. The derivatives of (x3 + ex + 3x + cot x) with respect to x is

  5. If \({\rm{y}} = {\cos ^{ - 1}}\left( {\frac{{2{\rm{x}}}}{{1 + {{\rm{x}}^2}}}} \right)\) , then \(\frac{{{\rm{dy}}}}{{{\rm{dx}}}}\) is equal to

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