Math Problem Statement

If f(x) = 3|x + 1| - 4 and g(x) = -2x^2 - 5, what is f(g(x))?

Solution

We are given two functions:

  • f(x)=3x+14f(x) = 3|x + 1| - 4
  • g(x)=2x25g(x) = -2x^2 - 5

We are asked to find f(g(x))f(g(x)), which means we will substitute g(x)g(x) into the function f(x)f(x).

Step-by-step solution:

  1. g(x)=2x25g(x) = -2x^2 - 5, so we substitute g(x)g(x) into f(x)f(x): f(g(x))=3g(x)+14f(g(x)) = 3 \left| g(x) + 1 \right| - 4 Substituting g(x)=2x25g(x) = -2x^2 - 5: f(g(x))=3(2x25)+14f(g(x)) = 3 \left| (-2x^2 - 5) + 1 \right| - 4

  2. Simplify the expression inside the absolute value: (2x25)+1=2x24(-2x^2 - 5) + 1 = -2x^2 - 4 So, we have: f(g(x))=32x244f(g(x)) = 3 \left| -2x^2 - 4 \right| - 4

  3. Since the absolute value of 2x24-2x^2 - 4 is 2x2+42x^2 + 4 (because the absolute value removes the negative sign), we have: f(g(x))=3(2x2+4)4f(g(x)) = 3(2x^2 + 4) - 4

  4. Now, distribute the 3: f(g(x))=6x2+124f(g(x)) = 6x^2 + 12 - 4

  5. Simplify the expression: f(g(x))=6x2+8f(g(x)) = 6x^2 + 8

Thus, f(g(x))=6x2+8f(g(x)) = 6x^2 + 8.


Would you like any further clarifications?

Here are five related questions to further your understanding:

  1. What happens if you change the sign inside the absolute value?
  2. How would the answer change if g(x)g(x) were linear instead of quadratic?
  3. Can you apply this process to a different pair of functions, say f(x)=x2f(x) = x^2 and g(x)=x+1g(x) = x + 1?
  4. What is the significance of the absolute value in the function f(x)f(x)?
  5. How would you differentiate f(g(x))f(g(x)) with respect to xx?

Tip:

Always handle absolute value expressions carefully by considering both positive and negative cases of the content inside the absolute value.

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Math Problem Analysis

Mathematical Concepts

Composition of functions
Absolute Value
Quadratic Equations

Formulas

f(x) = 3|x + 1| - 4
g(x) = -2x^2 - 5
f(g(x)) = 3|g(x) + 1| - 4

Theorems

Properties of Absolute Value

Suitable Grade Level

Grades 10-12