Math Problem Statement

f(x) = 4x + 3 and g(x) = 2 - 3x find (g.f)(3)

Solution

To find (gf)(3)(g \circ f)(3), we need to evaluate the composition of the functions g(x)g(x) and f(x)f(x) at x=3x = 3. This composition is defined as:

(gf)(x)=g(f(x))(g \circ f)(x) = g(f(x))

Given Functions

  • f(x)=4x+3f(x) = 4x + 3
  • g(x)=23xg(x) = 2 - 3x

Step-by-Step Solution

  1. Calculate f(3)f(3):

    Substitute x=3x = 3 into f(x)f(x):

    f(3)=4(3)+3f(3) = 4(3) + 3 f(3)=12+3f(3) = 12 + 3 f(3)=15f(3) = 15

  2. Calculate g(f(3))=g(15)g(f(3)) = g(15):

    Now substitute f(3)=15f(3) = 15 into g(x)g(x):

    g(15)=23(15)g(15) = 2 - 3(15) g(15)=245g(15) = 2 - 45 g(15)=43g(15) = -43

Conclusion

(gf)(3)=43(g \circ f)(3) = -43

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

Related Questions:

  1. What is (fg)(3)(f \circ g)(3) given the functions above?
  2. How do you find (gg)(x)(g \circ g)(x) for any xx?
  3. What is the slope and y-intercept of the functions f(x)f(x) and g(x)g(x)?
  4. How can you find the inverse of g(x)=23xg(x) = 2 - 3x?
  5. How would you solve (gf)(x)=0(g \circ f)(x) = 0?

Tip:

To compute (gf)(x)(g \circ f)(x), always evaluate f(x)f(x) first, then substitute its value into g(x)g(x).

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Math Problem Analysis

Mathematical Concepts

Function Composition
Linear Functions

Formulas

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Theorems

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Suitable Grade Level

Grades 10-12