Mirror Points

Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 5 of 61.

Change the sign of y in (3, 2), and you get (3, -2). It is straight below (3, 2). Change the sign of x instead, and you get (-3, 2). It is straight across, on the other side.

$(3, 2) with its mirror images (3, -2) below and (-3, 2) to the left$

These are mirror images. Changing the sign of y mirrors a point across the x-axis. Changing the sign of x mirrors it across the y-axis.

Challenge

The point (-4, 3) is drawn. Place its mirror image across the x-axis, and its mirror image across the y-axis. Drag each dot to its spot on the grid.

Try it yourself

Place the points

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 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 QuadrantsMirror PointsOn 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