Ax + By = C

Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 28 of 64.

A linear equation can also be written in standard form, Ax + By = C, where A and B are not both zero. For example, 2x + 3y = 12. Setting one coordinate to zero lets you find an intercept, if it exists.

On the x-axis, y = 0. Substituting into 2x + 3y = 12 gives 2x = 12, so the x-intercept is (6, 0).

Challenge

Medium

The line 3x + 4y = 24 crosses the x-axis where y = 0. Find the x value of that crossing.

Try it yourself

3x + 4y = 24y = 0

Solve for x

Test yourself

This 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 Point The Four Quadrants Points on the Axes Mirror Points Recap: The Plane

4Slope-Intercept Form

y = mx + b The Starting Height Write the Equation Solve for y Draw From Any Form Recap: y = mx + b

7Parallel & Perpendicular

Same Slope, Never Meet The Perpendicular Slope A Right-Angle Line Recap: Two Relations

10Systems by Graphing

Two Lines, One Answer Solve by Drawing Check the Crossing When Lines Never Cross Recap: By Graphing

2From Rule to Line

A Rule Makes Points The Points Line Up On the Line or Not?Between the Dots Recap: Rule to Line

5Point-Slope Form

A Point and a Slope From Two Points Flat or Vertical Through Draw From a Point Recap: Point-Slope

8Function Notation

The Name of a Rule Inputs With Signs Find the Input The Graph of f Recap: f(x)

11Solving Systems Exactly

Substitution Isolate First Elimination Scale, Then Add Three Unknowns Two Numbers, Two Facts Recap: Two Methods