Algebraic proof

What you'll learn

1. 1

   Think of a number trick: 'Pick a number, double it, add 4, halve it, subtract 2.' You always get back your original number! 🎩

2. 2

   What does the letter 'n' stand for in algebraic proof?

3. 3

   Let's prove the trick 'Think of a number, add 3, double it, subtract 6' always gives back your number.

4. 4

   What does 2(n + 3) simplify to?

5. 5

   Use the number line to see the trick: start at n, add 3, then double it. What do you get?

6. 6

   Which expression shows 'double n, then add 5'?

7. 7

   Prove that adding 5 to a number, then subtracting 5 gives back your number.