Repeat Exercise 3(a) using extrapolation with h0 = 0.2, h1 = h0/2, and h2 = h0/4. Repeat

Question:

Repeat Exercise 3(a) using extrapolation with h0 = 0.2, h1 = h0/2, and h2 = h0/4.
Repeat exercise 3(a)
a. ∂2u / ∂x2 + ∂2u / ∂y2 = 0, 0 < x < 1, 0 < y < 1;
u(x, 0) = 0, u(x, 1) = x,...............0≤ x ≤ 1;
u(0, y) = 0, u(1, y) = y, ...............0≤ y ≤ 1.