(a) Apply this to p₁(9.2) and p₂(9.2) for the data x₀ = 9.0, x₁ = 9.5, x₂ = 11.0, f₀ = ln x₀, f₁ = ln x₁, f₂ = ln x₂ (6S-values).

(b) Given (x_j, f(x_j)) = (0.2, 0.9980), (0.4, 0.9686), (0.6, 0.8443), (0.8, 0.5358), (1.0, 0). Find f(0.7) from the quadratic interpolation polynomials based on (α) 0.6, 0.8, 1.0, (β) 0.4, 0.6, 0.8, (γ) 0.2, 0.4, 0.6. Compare the errors and comment. [Exact f(x) = cos (1/2πx²), f(0.7) = 0.7181 (4S).]