Square roots

A puzzle with x², and a new spell: √.

What it looks like

x² = 25

√ is the square root spell. It undoes a square.

√25 asks: what number times itself makes 25? The answer is 5.

This spell needs no number. You just cast it.

Worked example 1

  1. x² = 25

  2. Apply square root to both sides

  3. x = 5

Check it: 5 times 5 is 25. It works.

Worked example 2

  1. 3x² = 75

  2. Divide both sides by 3

  3. x² = 25

  4. Apply square root to both sides

  5. x = 5

Divide first. If you try the square root spell on 3x², the wizard stops you. He says, "The square root spell needs a pure square to work on — simplify first!"

The most common mistake

Thinking square root means "half".

Not this

√16 is half of 16

8

But 8 times 8 is 64.

This

√16 is the number that times itself makes 16

4

And 4 times 4 is 16.

Good to know

The game always uses the answer that is above zero. Older players may know that −5 times −5 is also 25.

In the game

You meet these puzzles in the Shadow Spire.

Back to the game