Math Problem Statement

the function f is defined by f:x->x-3. another function g is such that gf:x->(x^2)+2. find function g

Solution

Given the functions f:xx3f: x \to x - 3 and gf:xx2+2gf: x \to x^2 + 2, we need to find the function g(x)g(x).

Let's denote f(x)=x3f(x) = x - 3. The composition g(f(x))=x2+2g(f(x)) = x^2 + 2.

Step 1: Express g(f(x))g(f(x))

Given that g(f(x))=x2+2g(f(x)) = x^2 + 2, and knowing f(x)=x3f(x) = x - 3, substitute f(x)f(x) into the equation:

g(f(x))=g(x3)g(f(x)) = g(x - 3)

So, the equation becomes:

g(x3)=x2+2g(x - 3) = x^2 + 2

Step 2: Solve for g(x)g(x)

To find g(x)g(x), replace x3x - 3 with some variable uu so that:

u=x3u = x - 3

Then, x=u+3x = u + 3, and the equation becomes:

g(u)=(u+3)2+2g(u) = (u + 3)^2 + 2

Step 3: Expand the expression

Now, expand (u+3)2(u + 3)^2:

g(u)=(u+3)2+2=u2+6u+9+2=u2+6u+11g(u) = (u + 3)^2 + 2 = u^2 + 6u + 9 + 2 = u^2 + 6u + 11

Thus, the function g(x)g(x) is:

g(x)=x2+6x+11g(x) = x^2 + 6x + 11

Final Answer:

The function g(x)g(x) is g(x)=x2+6x+11g(x) = x^2 + 6x + 11.

Would you like more details or have any questions?

Here are 5 related questions:

  1. How do you verify that the function g(x)g(x) is correct?
  2. What is the composition of f(g(x))f(g(x))?
  3. How does the function g(x)=x2+6x+11g(x) = x^2 + 6x + 11 behave graphically?
  4. Can you find g(x)g(x) if gf:xx22x+1gf:x \to x^2 - 2x + 1?
  5. How would the function g(x)g(x) change if f(x)=2x3f(x) = 2x - 3?

Tip: When dealing with composite functions, it’s often helpful to rewrite the functions in simpler terms to see how they interact.

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Math Problem Analysis

Mathematical Concepts

Functions
Composition of Functions
Quadratic Functions

Formulas

g(x) = x^2 + 6x + 11

Theorems

Function Composition

Suitable Grade Level

Grades 10-12