Math Problem Statement

tentukan

Tentukan nilai dari (f o g)(0), (g o f)(3), dan solusi dari (g o f)(x) = 8, maka x?

Solution

From the image you provided, the question appears to involve composite functions, where f(x)f(x) and g(x)g(x) are given as:

  1. f(x)=2x+1f(x) = 2x + 1
  2. g(x)=x23x+4g(x) = x^2 - 3x + 4

The task is to find various composite functions and values, such as:

  • (fg)(0)(f \circ g)(0)
  • (gf)(3)(g \circ f)(3)
  • (gf)(x)=8(g \circ f)(x) = 8, solve for xx

Step-by-Step Solution:

1. (fg)(0)(f \circ g)(0)

This is the value of f(g(0))f(g(0)).

  • First, find g(0)g(0): g(0)=023(0)+4=4g(0) = 0^2 - 3(0) + 4 = 4
  • Now, substitute g(0)=4g(0) = 4 into f(x)f(x): f(4)=2(4)+1=8+1=9f(4) = 2(4) + 1 = 8 + 1 = 9 Thus, (fg)(0)=9(f \circ g)(0) = 9.

2. (gf)(3)(g \circ f)(3)

This is the value of g(f(3))g(f(3)).

  • First, find f(3)f(3): f(3)=2(3)+1=6+1=7f(3) = 2(3) + 1 = 6 + 1 = 7
  • Now, substitute f(3)=7f(3) = 7 into g(x)g(x): g(7)=723(7)+4=4921+4=32g(7) = 7^2 - 3(7) + 4 = 49 - 21 + 4 = 32 Thus, (gf)(3)=32(g \circ f)(3) = 32.

3. Solve (gf)(x)=8(g \circ f)(x) = 8

This means we need to solve for xx such that g(f(x))=8g(f(x)) = 8.

  • First, find f(x)f(x): f(x)=2x+1f(x) = 2x + 1
  • Now, substitute f(x)f(x) into g(x)g(x): g(f(x))=(2x+1)23(2x+1)+4g(f(x)) = (2x + 1)^2 - 3(2x + 1) + 4
  • Simplify the expression: (2x+1)2=4x2+4x+1(2x + 1)^2 = 4x^2 + 4x + 1 3(2x+1)=6x3-3(2x + 1) = -6x - 3 g(f(x))=4x2+4x+16x3+4=4x22x+2g(f(x)) = 4x^2 + 4x + 1 - 6x - 3 + 4 = 4x^2 - 2x + 2
  • Now, solve 4x22x+2=84x^2 - 2x + 2 = 8: 4x22x+28=04x^2 - 2x + 2 - 8 = 0 4x22x6=04x^2 - 2x - 6 = 0 Divide through by 2: 2x2x3=02x^2 - x - 3 = 0
  • Solve using the quadratic formula: x=(1)±(1)24(2)(3)2(2)x = \frac{-(-1) \pm \sqrt{(-1)^2 - 4(2)(-3)}}{2(2)} x=1±1+244=1±254x = \frac{1 \pm \sqrt{1 + 24}}{4} = \frac{1 \pm \sqrt{25}}{4} x=1±54x = \frac{1 \pm 5}{4} Thus, x=1+54=64=1.5x = \frac{1 + 5}{4} = \frac{6}{4} = 1.5 or x=154=44=1x = \frac{1 - 5}{4} = \frac{-4}{4} = -1.

So, the solutions are x=1.5x = 1.5 and x=1x = -1.


Would you like more details or have any questions?

Here are 5 related questions for further practice:

  1. What is (fg)(x)(f \circ g)(x) in general form?
  2. How would you solve (fg)(x)=5(f \circ g)(x) = 5?
  3. Can you find (gf)(0)(g \circ f)(0)?
  4. What are the solutions to g(f(x))=16g(f(x)) = 16?
  5. If f(x)=3x2f(x) = 3x - 2 and g(x)=x2+x+1g(x) = x^2 + x + 1, what is (fg)(2)(f \circ g)(2)?

Tip: Always check the order of composition carefully—f(g(x))f(g(x)) is not the same as g(f(x))g(f(x))!

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Math Problem Analysis

Mathematical Concepts

Algebra
Composite Functions
Quadratic Equations

Formulas

f(x) = 2x + 1
g(x) = x^2 - 3x + 4
(f o g)(x) = f(g(x))
(g o f)(x) = g(f(x))
Quadratic formula: x = (-b ± √(b² - 4ac)) / 2a

Theorems

Quadratic formula

Suitable Grade Level

Grade 10-12