Equation balance – linear equations in two variables

MathematicsAlgebraAges 14–15

Place x, y and constant algebra tiles (positive tiles are coloured, negative tiles have a white border) on the two pans of a balance to build a linear equation in two variables of the form ax + by + c = a'x + b'y + c'. Drag the two sliders to change x and y and see whether the balance levels out, finding many different solution pairs (x, y) for the same equation. Turn on the lock to see that adding the same tile to both sides always keeps the balance unchanged. Adapted from the "Equality Explorer: Two Variables" simulation by PhET Interactive Simulations, University of Colorado Boulder (CC BY 4.0); rewritten.

Lesson: Linear equations in two variables