Solve by Drawing
Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 50 of 64.
To solve a system by graphing, draw both lines and read where they cross. Take y = 2x - 3; y = -x + 3. The first line crosses the y-axis at (0, -3) and has slope 2. The second line crosses the y-axis at (0, 3) and has slope -1. The two lines meet at (2, 1). That point is the solution, x = 2 and y = 1.
An intersection at (2, 1) can be read from the grid. If the intersection falls between grid marks, its coordinates may be difficult to read accurately. Algebraic methods can give the exact solution.
Challenge
MediumDraw both lines of y = x - 3; y = -3x + 5 and read off where they cross.
Try it yourself
Draw the graph
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Graphs & Systems
1The Coordinate Plane
Two Numbers, One PointThe Four QuadrantsPoints on the AxesMirror PointsRecap: The Plane4Slope-Intercept Form
y = mx + bThe Starting HeightWrite the EquationSolve for yDraw From Any FormRecap: y = mx + b7Parallel & Perpendicular
Same Slope, Never MeetThe Perpendicular SlopeA Right-Angle LineRecap: Two Relations10Systems by Graphing
Two Lines, One AnswerSolve by DrawingCheck the CrossingWhen Lines Never CrossRecap: By Graphing2From Rule to Line
A Rule Makes PointsThe Points Line UpOn the Line or Not?Between the DotsRecap: Rule to Line