Given the non-uniform grid as follows: A1 Uj-1 uj Uj+1 Figure 1: Non-uniform grid. The spacing between u;_1 and u; is Ax, and between Ax1 Ax2 and Uj+1 is Ax2, 1. Derive a 3-point central differencing scheme for the second derivative using the solution values at j- 1, j, j + 1 . 2. What is the error term and the order of accuracy for the above scheme?