Differentiate the following functions using the appropriate notation: a) g(x) = 4/x^3 b) y = (x^3 - 5x)/x

Question image

Understand the Problem

The question is asking us to find the derivative of two functions a) g(x) = 4/x^3 and b) y = (x^3 - 5x)/x. For each function, we need to apply the appropriate differentiation rules and notation to find the derivative.

Answer

a) $g'(x) = -\frac{12}{x^4}$ b) $\frac{dy}{dx} = 2x$
Answer for screen readers

a) $g'(x) = -\frac{12}{x^4}$ b) $\frac{dy}{dx} = 2x$

Steps to Solve

  1. Rewrite the function g(x)

Rewrite the function $g(x) = \frac{4}{x^3}$ using a negative exponent to make it easier to differentiate.

$g(x) = 4x^{-3}$

  1. Differentiate g(x) using the power rule

Apply the power rule for differentiation, which states that if $f(x) = ax^n$, then $f'(x) = nax^{n-1}$.

$g'(x) = -3 \cdot 4x^{-3-1}$ $g'(x) = -12x^{-4}$

  1. Rewrite g'(x) with a positive exponent

Rewrite the derivative with a positive exponent:

$g'(x) = -\frac{12}{x^4}$

  1. Simplify the function y

Simplify $y = \frac{x^3 - 5x}{x}$ by dividing each term in the numerator by $x$:

$y = \frac{x^3}{x} - \frac{5x}{x}$ $y = x^2 - 5$

  1. Differentiate y using the power rule

Differentiate $y = x^2 - 5$ with respect to $x$. The derivative of $x^2$ is $2x$, and the derivative of a constant (-5) is 0.

$\frac{dy}{dx} = 2x - 0$ $\frac{dy}{dx} = 2x$

a) $g'(x) = -\frac{12}{x^4}$ b) $\frac{dy}{dx} = 2x$

More Information

The power rule is a fundamental concept in differential calculus. It allows us to easily find the derivative of power functions which is shown in both parts of this question.

Tips

  • Forgetting to rewrite the original function with negative exponents before differentiating.
  • Incorrectly applying the power rule (e.g., not multiplying by the exponent or not subtracting 1 from the exponent).
  • Not simplifying the function before differentiating (part b), which can make the differentiation process more complex.
  • Forgetting that the derivative of a constant is zero.

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