Can someone explain how to do part b?

3

Step-by-step explanation:

4(a) The first 3 terms are:

₅C₀ (3)⁵ (bx)⁰ = 1 × 3⁵ × 1 = 243

₅C₁ (3)⁴ (bx)¹ = 5 × 3⁴ × bx = 405b x

₅C₂ (3)³ (bx)² = 10 × 3³ × (bx)² = 270b² x²

4(b) The coefficient of x² (the third term) is twice the coefficient of x (the second term).

270b² = 2 (405 b)

270b² = 810b

270b = 810

b = 3

3

Step-by-step explanation:

Term in x²: 270b²x²

Coefficient: 270b²

Term in x: 405bx

Coefficient: 405b

270b² = 2(405b)

270b² - 810b = 0

270b(b - 3) = 0

b = 0, 3

Since b is non-zero,

b = 3

step-by-step explanation: