AlgebraLab

Algebra I Recipe: Quick Graphs Using Intercepts

By G Redden

A. Definitions
  1. x-intercept – the point where the line crosses the x-axis.
  2. y-intercept – the point where the line crosses the y-axis.
B. How to Graph Using the x and y Intercepts
  1. Find the x-intercept.
    • Substitute zero in place of y in the equation.
    • Solve the equation for x.
    • You get the ordered pair (x, 0).
  2. Find the y-intercept.
    • Substitute zero in place of x in the equation.
    • Solve the equation for y.
    • You get the ordered pair (0, y).
  3. Graph the two intercepts or points.
  4. Connect the points with a straight line and arrows on each end.
  5. Label the line with its equation.
1.
2x + 3y = 6
2.
3.5x + 7y = 14
3.
y = 4x + 40
4.
Extension: You are organizing a lasagna dinner to raise funds for your new school. Your goal is to sell $2880 worth of tickets. Assuming 300 adults and 120 students will attend the dinner, how much could you charge for an adult ticket and for a student ticket?