Math Problem Statement

Find the derivative of the functions g(x) = x^3 - 8x, h(x) = 3x^2 + 2x, and f(x) = (x^3 - 8x)(3x^2 + 2x).

Solution

Let's work through the derivatives of each function given in the image.

The functions are:

  1. g(x)=x38xg(x) = x^3 - 8x
  2. h(x)=3x2+2xh(x) = 3x^2 + 2x
  3. f(x)=(x38x)(3x2+2x)f(x) = (x^3 - 8x)(3x^2 + 2x)

Step-by-step solutions:

1. g(x)g'(x) (Derivative of g(x)=x38xg(x) = x^3 - 8x)

  • Apply the power rule: ddx[xn]=nxn1\frac{d}{dx} [x^n] = nx^{n-1}
  • Derivative of x3x^3 is 3x23x^2
  • Derivative of 8x-8x is 8-8

Thus, g(x)=3x28g'(x) = 3x^2 - 8

2. h(x)h'(x) (Derivative of h(x)=3x2+2xh(x) = 3x^2 + 2x)

  • Derivative of 3x23x^2 is 6x6x
  • Derivative of 2x2x is 22

Thus, h(x)=6x+2h'(x) = 6x + 2

3. f(x)f'(x) (Derivative of f(x)=(x38x)(3x2+2x)f(x) = (x^3 - 8x)(3x^2 + 2x))

  • Use the product rule: ddx[u(x)v(x)]=u(x)v(x)+u(x)v(x)\frac{d}{dx} [u(x) \cdot v(x)] = u'(x)v(x) + u(x)v'(x)
  • Let u(x)=x38xu(x) = x^3 - 8x and v(x)=3x2+2xv(x) = 3x^2 + 2x

First, find the derivatives of u(x)u(x) and v(x)v(x):

  • u(x)=3x28u'(x) = 3x^2 - 8
  • v(x)=6x+2v'(x) = 6x + 2

Now apply the product rule: f(x)=u(x)v(x)+u(x)v(x)f'(x) = u'(x) v(x) + u(x) v'(x) f(x)=(3x28)(3x2+2x)+(x38x)(6x+2)f'(x) = (3x^2 - 8)(3x^2 + 2x) + (x^3 - 8x)(6x + 2) Now expand both terms:

  1. (3x28)(3x2+2x)=9x4+6x324x216x(3x^2 - 8)(3x^2 + 2x) = 9x^4 + 6x^3 - 24x^2 - 16x
  2. (x38x)(6x+2)=6x4+2x348x216x(x^3 - 8x)(6x + 2) = 6x^4 + 2x^3 - 48x^2 - 16x

Combine like terms: f(x)=9x4+6x324x216x+6x4+2x348x216xf'(x) = 9x^4 + 6x^3 - 24x^2 - 16x + 6x^4 + 2x^3 - 48x^2 - 16x f(x)=15x4+8x372x232xf'(x) = 15x^4 + 8x^3 - 72x^2 - 32x

Thus, f(x)=15x4+8x372x232xf'(x) = 15x^4 + 8x^3 - 72x^2 - 32x.


Would you like more details on any of these steps?

Here are 5 related questions to help expand your understanding:

  1. What is the power rule for differentiation?
  2. How does the product rule work, and when should you use it?
  3. Can you apply the chain rule to composite functions during differentiation?
  4. How would you find the second derivative of the function g(x)g(x)?
  5. How do you factor a polynomial after differentiating?

Tip: Always simplify your expression after applying the product or chain rule to avoid complex terms.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Product Rule
Power Rule

Formulas

Power Rule: d/dx [x^n] = nx^{n-1}
Product Rule: d/dx [u(x) * v(x)] = u'(x)v(x) + u(x)v'(x)

Theorems

Product Rule for Differentiation

Suitable Grade Level

Grades 11-12