Question

Evaluate the following.

1. 10C₄

2. 21C₃

3. 19C₁₅

4. 31C₂₉ 

Answer 1

1. 10C₄ = \(\frac{10 \times 9 \times 8 \times 7}{1 \times 2 \times 3 \times 4} \) = 10 × 3 × 7 = 210

2. 21C₃ = \(\frac{21 \times 20 \times 19}{1 \times 2 \times 3}\) = 7 × 10 × 19 = 1330

3. 19C₁₅ = \(\frac{19 \times 18 \times 17 \times 16}{1 \times 2 \times 3 \times 4}\) = 19 × 3 × 17 × 4 = 3876

4. 31C₂₉ = \(\frac{31 \times 30}{1 \times 2}\) = 465.