Math Problem Statement

The function g is defined by f such that g(x) = 3f(ax)+1 if(x) =x^2-3x and g(2) =1 what is the value for all a>0?

Solution

We are given two functions and a specific condition. Let's break this down to find the value of aa when a>0a > 0.

Step 1: Function Definition

  • We are told that g(x)=3f(ax)+1g(x) = 3f(ax) + 1.
  • Additionally, we know f(x)=x23xf(x) = x^2 - 3x.

Thus, the function g(x)g(x) becomes: g(x)=3f(ax)+1=3((ax)23(ax))+1=3(a2x23ax)+1.g(x) = 3f(ax) + 1 = 3\left( (ax)^2 - 3(ax) \right) + 1 = 3\left( a^2x^2 - 3ax \right) + 1. Simplifying this expression: g(x)=3a2x29ax+1.g(x) = 3a^2x^2 - 9ax + 1.

Step 2: Use the Condition g(2)=1g(2) = 1

We are also given that g(2)=1g(2) = 1. Substituting x=2x = 2 into the equation for g(x)g(x): g(2)=3a2(2)29a(2)+1=1.g(2) = 3a^2(2)^2 - 9a(2) + 1 = 1. Simplifying this: g(2)=3a2(4)18a+1=1,g(2) = 3a^2(4) - 18a + 1 = 1, 12a218a+1=1.12a^2 - 18a + 1 = 1. Subtract 1 from both sides: 12a218a=0.12a^2 - 18a = 0.

Step 3: Solve the Equation for aa

Factor the equation: 6a(2a3)=0.6a(2a - 3) = 0. This gives two possible solutions: a=0ora=32.a = 0 \quad \text{or} \quad a = \frac{3}{2}.

Step 4: Consider a>0a > 0

Since we are told that a>0a > 0, we reject a=0a = 0 and conclude that: a=32.a = \frac{3}{2}.

Thus, the value of aa is 32\frac{3}{2} for all a>0a > 0.

Would you like further details or have any questions about this solution?

Here are 5 related questions to expand your understanding:

  1. How do you factor a quadratic expression like 12a218a=012a^2 - 18a = 0?
  2. Can you explain why a=0a = 0 is not a valid solution in this case?
  3. How would the solution change if f(x)f(x) was a different quadratic function?
  4. What happens to g(x)g(x) if f(x)f(x) has an added constant term?
  5. Can you derive the general form of g(x)g(x) for any function f(x)f(x)?

Tip: Always verify your solution by substituting it back into the original equation to check its validity.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Function Composition

Formulas

Quadratic equation formula: ax^2 + bx + c = 0
Function composition: g(x) = 3f(ax) + 1

Theorems

Factoring quadratic equations

Suitable Grade Level

Grades 9-12