Proof Fidget

Objective

Start from an equation and reach the goal, usually with x isolated on one side. Each legal step writes a new line of a finished proof.

Doing the same to both sides

• If you add, subtract, multiply or divide, you must do it to both sides.
• That keeps the two sides equal, so the new line is still true.
• A step that is true of some other equation, but does not help from here, is rejected.

Expanding brackets

On Classic and Hard proofs you often expand brackets, collect like terms, then isolate x. If two openings are both legal (for example expand, or divide both sides first), either is accepted and the later lines follow the path you chose.

Controls

• Tap a transformation to apply it at once.
• Hint applies a valid next step. Undo takes the last line back.

Difficulty

• Easy: two-step linear equations such as 3x + 6 = 18.
• Classic: three-step proofs, including brackets and variables on both sides.
• Hard: four-step proofs: expand, collect, then solve.

Daily challenge

Everyone receives the same seeded Classic proof. It resets at midnight UK. The first solve of the day counts for the league and your streak.