Math Problem Statement

Diketahui fungsi f(x) = 2x^2 - 5x + 3 dan g(x) = x + 4. Tentukan (f + g)(6) dan (f ⋅ g)(-2).

Solution

The problem in the image asks us to evaluate two expressions involving functions ff and gg.

Given: f(x)=2x25x+3f(x) = 2x^2 - 5x + 3 g(x)=x+4g(x) = x + 4

We are asked to find:

  1. (f+g)(6)(f + g)(6)
  2. (fg)(2)(f \cdot g)(-2)

Solution

  1. Finding (f+g)(6)(f + g)(6):

    (f+g)(x)=f(x)+g(x)(f + g)(x) = f(x) + g(x) Substitute f(x)=2x25x+3f(x) = 2x^2 - 5x + 3 and g(x)=x+4g(x) = x + 4: (f+g)(x)=(2x25x+3)+(x+4)(f + g)(x) = (2x^2 - 5x + 3) + (x + 4) Simplify by combining like terms: (f+g)(x)=2x24x+7(f + g)(x) = 2x^2 - 4x + 7 Now, substitute x=6x = 6: (f+g)(6)=2(6)24(6)+7(f + g)(6) = 2(6)^2 - 4(6) + 7 =23624+7= 2 \cdot 36 - 24 + 7 =7224+7= 72 - 24 + 7 =55= 55

  2. Finding (fg)(2)(f \cdot g)(-2):

    (fg)(x)=f(x)g(x)(f \cdot g)(x) = f(x) \cdot g(x) Substitute f(x)=2x25x+3f(x) = 2x^2 - 5x + 3 and g(x)=x+4g(x) = x + 4: (fg)(x)=(2x25x+3)(x+4)(f \cdot g)(x) = (2x^2 - 5x + 3)(x + 4) We expand this expression: (fg)(x)=2x3+8x25x220x+3x+12(f \cdot g)(x) = 2x^3 + 8x^2 - 5x^2 - 20x + 3x + 12 Combine like terms: (fg)(x)=2x3+3x217x+12(f \cdot g)(x) = 2x^3 + 3x^2 - 17x + 12 Now, substitute x=2x = -2: (fg)(2)=2(2)3+3(2)217(2)+12(f \cdot g)(-2) = 2(-2)^3 + 3(-2)^2 - 17(-2) + 12 =2(8)+3(4)+34+12= 2(-8) + 3(4) + 34 + 12 =16+12+34+12= -16 + 12 + 34 + 12 =42= 42

Final Answers:

  1. (f+g)(6)=55(f + g)(6) = 55
  2. (fg)(2)=42(f \cdot g)(-2) = 42

Would you like further details on these calculations or explanations?

Here are some related questions to deepen understanding:

  1. How do you find the sum of two functions in general?
  2. How can you simplify the product of two functions?
  3. What is the significance of evaluating a function at a specific point?
  4. How would the process change if g(x)g(x) were a quadratic function?
  5. How do you apply polynomial multiplication in function composition?

Tip: Always combine like terms after expanding to simplify expressions efficiently.

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Math Problem Analysis

Mathematical Concepts

Algebra
Functions
Function Addition
Function Multiplication

Formulas

(f + g)(x) = f(x) + g(x)
(f ⋅ g)(x) = f(x) ⋅ g(x)

Theorems

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Suitable Grade Level

Grades 10-12