Math Problem Statement

Graph the inequality x-y<3

Solution

To graph the inequality xy<3x - y < 3, we can follow these steps:

Step 1: Rewrite the inequality in slope-intercept form (if possible)

We want to isolate yy on one side. Start by subtracting xx from both sides of the inequality:

x+xy<3x-x + x - y < 3 - x

y<x+3-y < -x + 3

Now multiply both sides by -1. Remember, when multiplying or dividing by a negative number, the inequality sign flips:

y>x3y > x - 3

So, the inequality is now y>x3y > x - 3.

Step 2: Graph the boundary line

The equation y=x3y = x - 3 is the boundary line of the inequality. This is a line with:

  • Slope = 1 (since the coefficient of xx is 1),
  • Y-intercept = -3 (since the constant term is -3).

To graph this line, plot the y-intercept at (0,3)(0, -3), then use the slope (rise over run) of 1 to move up 1 unit and 1 unit to the right, plotting another point at (1,2)(1, -2). Draw a straight line through these points.

Step 3: Determine which side of the line to shade

The inequality is y>x3y > x - 3, meaning the solution consists of all points above the line y=x3y = x - 3.

To confirm, you can pick a test point that is not on the line. A good test point is the origin (0,0)(0, 0). Substitute x=0x = 0 and y=0y = 0 into the inequality:

0>030 > 0 - 3

0>3(True)0 > -3 \quad \text{(True)}

Since the test point satisfies the inequality, we shade the region above the line.

Final Graph:

  1. The boundary line y=x3y = x - 3 is drawn as a dashed line because the inequality is strict (<<, not \leq).
  2. The shaded region will be above this line.

Would you like to see a visual representation of the graph or have any other questions about graphing inequalities?


Here are five related questions you might find interesting:

  1. How do you graph inequalities involving \leq or \geq?
  2. What if the inequality was x+2y>4x + 2y > 4? How would the graph change?
  3. How do you graph inequalities in two variables that have an "and" condition (e.g., y<3x+1y < 3x + 1 and y>x2y > x - 2)?
  4. How can you determine the solution set for a system of linear inequalities?
  5. What would happen if the inequality was yx3y \leq x - 3 instead?

Tip: When graphing inequalities, always check if the inequality is strict (using a dashed line) or non-strict (using a solid line) before shading!

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Math Problem Analysis

Mathematical Concepts

Algebra
Graphing Inequalities
Linear Equations

Formulas

Slope-intercept form: y = mx + b

Theorems

Properties of Inequalities
Graphing Linear Inequalities

Suitable Grade Level

Grades 8-10