Math Problem Statement

If f(x) is a linear function, f(-2) = -5, and f(3) = 3, find an equation for f(x).

Solution

The problem asks to find the equation of a linear function f(x)f(x), given that:

  • f(2)=5f(-2) = -5
  • f(3)=3f(3) = 3

Step-by-step solution:

  1. A linear function has the general form: f(x)=mx+bf(x) = mx + b where mm is the slope, and bb is the y-intercept.

  2. To find the slope mm, we use the slope formula: m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1} Using the points (2,5)(-2, -5) and (3,3)(3, 3): m=3(5)3(2)=3+53+2=85m = \frac{3 - (-5)}{3 - (-2)} = \frac{3 + 5}{3 + 2} = \frac{8}{5}

  3. Now that we have m=85m = \frac{8}{5}, substitute this into the linear function: f(x)=85x+bf(x) = \frac{8}{5}x + b

  4. To find bb, substitute one of the given points (e.g., (2,5)(-2, -5)) into the equation: 5=85(2)+b-5 = \frac{8}{5}(-2) + b Simplifying: 5=85×(2)+b=165+b-5 = \frac{8}{5} \times (-2) + b = \frac{-16}{5} + b Multiply both sides by 5 to eliminate the fraction: 25=16+5b-25 = -16 + 5b Solve for bb: 25+16=5b9=5bb=95-25 + 16 = 5b \quad \Rightarrow \quad -9 = 5b \quad \Rightarrow \quad b = -\frac{9}{5}

  5. Therefore, the equation of the linear function is: f(x)=85x95f(x) = \frac{8}{5}x - \frac{9}{5}

Would you like further clarification or more details?

Related Questions:

  1. How do you verify if a function is linear?
  2. Can you explain how to graph a linear function from its equation?
  3. What happens to the slope if the points are reversed?
  4. How would the equation change if f(x)f(x) were a quadratic function?
  5. What does the slope represent in real-world problems?

Tip:

When solving for the y-intercept in a linear function, substituting any given point into the equation ensures you accurately determine the correct value of bb.

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Math Problem Analysis

Mathematical Concepts

Linear Functions
Slope-Intercept Form
Algebra

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Linear equation form: f(x) = mx + b

Theorems

Point-Slope Theorem
Slope-Intercept Theorem

Suitable Grade Level

Grades 8-10