Math Problem Statement

If f(x) is a linear function, f(-3) = 3, and f(1) = -1, 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(3)=3f(-3) = 3
  • f(1)=1f(1) = -1

Step 1: Use the slope formula

Since the function is linear, its equation will be in the form:

f(x)=mx+bf(x) = mx + b

where mm is the slope and bb is the y-intercept.

The slope mm between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is calculated by the formula:

m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1}

Here, the points are (3,3)(-3, 3) and (1,1)(1, -1).

Substitute into the formula:

m=131(3)=44=1m = \frac{-1 - 3}{1 - (-3)} = \frac{-4}{4} = -1

Step 2: Use point-slope form to find the equation

Now that we know the slope m=1m = -1, we can use one of the given points to find bb. Let's use the point (1,1)(1, -1).

The equation is:

f(x)=x+bf(x) = -x + b

Substitute x=1x = 1 and f(1)=1f(1) = -1:

1=(1)+b    1=1+b-1 = -(1) + b \implies -1 = -1 + b

Solving for bb:

b=0b = 0

Final equation:

Thus, the equation for f(x)f(x) is:

f(x)=xf(x) = -x

Would you like further details on any part of the process?

Here are some related questions:

  1. How do you find the slope between two points?
  2. What is the significance of the slope in a linear function?
  3. Can a linear function have a slope of zero? What would that look like?
  4. How do you find the y-intercept from an equation?
  5. How can you verify if a point lies on a given line?

Tip: The slope tells you how steep the line is, and whether it increases or decreases as you move from left to right across the graph.

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Math Problem Analysis

Mathematical Concepts

Linear Functions
Algebra
Slope-Intercept Form

Formulas

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

Theorems

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Suitable Grade Level

Grades 8-10