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Write the Equation

Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 16 of 61.

To write a line's equation in slope-intercept form, substitute its slope for m and its y-intercept for b in $y = mx+b$ . A line with slope -2 passing through $\left(0, 5\right)$ has the following equation.

$y = -2x+5$

Here, $m = -2$ and $b = 5$ . If the same slope is paired with the intercept $\left(0, -3\right)$ , then $b = -3$ , giving $y = -2x-3$ .

A nonvertical line can be represented by a graph, a table of points, a description, or an equation. Use its slope and one point to write its equation.

Challenge

Medium

A line has slope -3 and y-intercept (0, 4). Write its equation.

Start the lesson to read it in the interactive player and track your progress.

All lessons in Graphs & Systems

1Points and Rules

Two Numbers, One Point A Rule Makes Points The Points Line Up

4Slope-Intercept Form

y = mx + b The Starting HeightWrite the EquationSolve 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

2The Whole Plane

The Four Quadrants Mirror Points On the Line or Not?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