Question: The coefficient of x<sup>4</sup> in the expansion of $\left( \frac{1–x}{1 + x} \right)^{2}$is –...

Question

The coefficient of x⁴ in the expansion of $\left( \frac{1–x}{1 + x} \right)^{2}$ is –

Answer 1

(1 – x)² (1 + x)^–2

= (1 – 2x + x²) (1 – 2x + 3x² – 4x³ + 5x⁴……)

= (5 + 8 + 3) = 16

Question: The coefficient of x<sup>4</sup> in the expansion of \(\left( \frac{1–x}{1 + x} \right)^{2}\)is –...