Binomial expansion (positive integer)

What you'll learn

1. 1

   Binomial expansion is a quick way to expand brackets like (x + y)² without writing out all the multiplications.

2. 2

   Here's the pattern for (x + y)²: x² + 2xy + y². The coefficients 1, 2, 1 come from Pascal's triangle!

3. 3

   Let's expand (x + 3)² together.

4. 4

   Now expand (2x + 1)² using the same pattern.

5. 5

   What is the coefficient of x in (x + 5)²?

6. 6

   Now try (3 + y)² — same pattern, just swap a and b.

7. 7

   Expand (x + 4)² — which is correct?