Math Problem Statement

A function f is given. f(x) = 9x + 8 (a) Sketch a graph of f.

Solution

To sketch the graph of the linear function f(x)=9x+8f(x) = 9x + 8, follow these steps:

Step 1: Identify the slope and y-intercept

The equation f(x)=9x+8f(x) = 9x + 8 is in the slope-intercept form y=mx+by = mx + b, where:

  • m=9m = 9 is the slope of the line.
  • b=8b = 8 is the y-intercept (the point where the line crosses the y-axis).

Step 2: Plot the y-intercept

The y-intercept occurs when x=0x = 0. Substituting x=0x = 0 into the function: f(0)=9(0)+8=8f(0) = 9(0) + 8 = 8 So, the point (0,8)(0, 8) is on the graph. Plot this point on the y-axis.

Step 3: Use the slope to find another point

The slope m=9m = 9 means that for every 1 unit increase in xx, yy increases by 9 units. Starting from the point (0,8)(0, 8), move 1 unit to the right (increasing xx by 1) and 9 units up (increasing yy by 9).

This gives another point: x=1,f(1)=9(1)+8=17x = 1, \quad f(1) = 9(1) + 8 = 17 So, the point (1,17)(1, 17) is also on the graph. Plot this point.

Step 4: Draw the line

Now, draw a straight line passing through the points (0,8)(0, 8) and (1,17)(1, 17). This line is the graph of the function f(x)=9x+8f(x) = 9x + 8.

Would you like me to generate a visual sketch of the graph for you?


Relative questions:

  1. What is the slope-intercept form of a line and how does it help in graphing?
  2. How would the graph change if the slope were negative, e.g., f(x)=9x+8f(x) = -9x + 8?
  3. What would be the graph's behavior if the y-intercept was 0?
  4. How do you determine points to plot from a given linear equation?
  5. How does the graph shift if the equation changes to f(x)=9x+5f(x) = 9x + 5?

Tip: Always check the slope to understand how steep the line will be and whether it is increasing or decreasing.

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Math Problem Analysis

Mathematical Concepts

Linear Functions
Graphing

Formulas

Slope-Intercept Form: y = mx + b

Theorems

Concept of Slope and Y-intercept

Suitable Grade Level

Grades 9-10