What is the distance of the point Q(2, 1) from the origin?

Correct answer: √5. Distance = √(x² + y²) = √(2² + 1²) = √5.

Background: The distance formula comes from the Pythagorean theorem.

• 3: 3 does not equal √5.
• √3: √3 does not equal √5.
• 2: 2 does not equal √5.

Did you know? √5 is about 2.24.

Memory trick: d = √(x² + y²).