Cracking Quadratics: Three Ways to Solve

1 of 4

Maths

Cracking Quadratics: Three Ways to Solve

3 more
1/4
For grown-ups

Companion summary

Have you ever wondered how a football reaches its highest point before falling back down? Engineers and game designers use quadratic equations every day to model curves, speed, and height. Here is one to keep: x squared minus five x plus six equals zero has two hidden answers, x equals two and x equals three. When you can spot those answers quickly, try solving one by completing the square — it is a superpower move.

Warm-Up: The Mystery Number

Warm-Up: The Mystery Number

Here is a puzzle: 'I think of a number. I multiply it by itself, then subtract 5 times the number. My answer is 6. What is my number?' Could there be more than one answer? Think about that — two different numbers might both work. This is the heart of a quadratic equation: unlike a simple equation with one solution, a quadratic can have two solutions. Let's find out why, and how to crack them every time.

💭 Think about this

Can you find two numbers that each satisfy: the number times itself, minus 5 times the number, equals 6? (Hint: try small whole numbers.)