Math Problem Statement

Given f(x) = x^2 - 3x + 4 and (f + g)(x) = 3x^2 + x - 5, determine: a. g(x), b. f(3) and g(3), c. (f + g)(3) and (f - g)(3).

Solution

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Given:

  • f(x)=x23x+4f(x) = x^2 - 3x + 4
  • (f+g)(x)=3x2+x5(f + g)(x) = 3x^2 + x - 5

To Find:

a. g(x)g(x)
b. f(3)f(3) and g(3)g(3)
c. (f+g)(3)(f + g)(3) and (fg)(3)(f - g)(3)


a. Finding g(x)g(x):

Since (f+g)(x)=f(x)+g(x)(f + g)(x) = f(x) + g(x), we can write: g(x)=(f+g)(x)f(x)g(x) = (f + g)(x) - f(x)

Substituting the given functions: g(x)=(3x2+x5)(x23x+4)g(x) = \left(3x^2 + x - 5\right) - \left(x^2 - 3x + 4\right) Simplifying the expression: g(x)=3x2+x5x2+3x4g(x) = 3x^2 + x - 5 - x^2 + 3x - 4 g(x)=(3x2x2)+(x+3x)+(54)g(x) = (3x^2 - x^2) + (x + 3x) + (-5 - 4) g(x)=2x2+4x9g(x) = 2x^2 + 4x - 9

So, g(x)=2x2+4x9g(x) = 2x^2 + 4x - 9.

b. Finding f(3)f(3) and g(3)g(3):

  • f(3)f(3): f(3)=323(3)+4=99+4=4f(3) = 3^2 - 3(3) + 4 = 9 - 9 + 4 = 4

  • g(3)g(3): g(3)=2(32)+4(3)9=2(9)+129=18+129=21g(3) = 2(3^2) + 4(3) - 9 = 2(9) + 12 - 9 = 18 + 12 - 9 = 21

So, f(3)=4f(3) = 4 and g(3)=21g(3) = 21.

c. Finding (f+g)(3)(f + g)(3) and (fg)(3)(f - g)(3):

  • (f+g)(3)(f + g)(3): (f+g)(3)=f(3)+g(3)=4+21=25(f + g)(3) = f(3) + g(3) = 4 + 21 = 25

  • (fg)(3)(f - g)(3): (fg)(3)=f(3)g(3)=421=17(f - g)(3) = f(3) - g(3) = 4 - 21 = -17

So, (f+g)(3)=25(f + g)(3) = 25 and (fg)(3)=17(f - g)(3) = -17.


Do you want more details or have any questions?

Related Questions:

  1. How do you find the difference of two functions?
  2. What happens when you subtract a quadratic function from another quadratic function?
  3. How does the value of g(x)g(x) change when you modify f(x)f(x) or (f+g)(x)(f + g)(x)?
  4. Can you explain how to factor a quadratic function like g(x)g(x)?
  5. What would happen if the coefficient of x2x^2 in (f+g)(x)(f + g)(x) were different?

Tip: Always substitute carefully when working with algebraic expressions, especially when subtracting functions.

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Math Problem Analysis

Mathematical Concepts

Algebra
Functions
Quadratic Equations
Function Operations

Formulas

(f + g)(x) = f(x) + g(x)
Substituting specific values into functions
Combining like terms in algebraic expressions

Theorems

Function Addition and Subtraction

Suitable Grade Level

Grades 9-10