The Points Line Up

Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 3 of 61.

The four points of $y = 2x-3$ were on one straight line. This always happens with a rule like this one: every point of the rule lies on one straight line. We call that line the graph of the rule.

$The line y = x + 1 drawn through the points (0, 1) and (2, 3)$

Only one straight line goes through two points. So you need only two points to draw it.

Challenge

Draw the line $y = x-2$ . Drag the two dots to two points of the rule. The line goes through both dots.

Try it yourself

y = x-2

Draw the line

All lessons in Graphs & Systems

1Points and Rules

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

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

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