Compute each of these double sums.

SolutionStep 1In this problem, we have to find the double sum.a)Here, we have to evaluate = (i - 1) + (i - 2) = 2i - 3 = 2i - 3 = 2 i - 3Now we have to evaluate i = 1 + 2 + 3 = 6 and 3 = 3 + 3 + 3 = 9Substitute the value back in a previous equation = 2 i - 3 = 2 * 6 - 9 = 12 - 9 = 3Hence, = 3Step 2b)(3i + 2j)Here, we have to evaluate (3i + 2j) (3i + 2j) = (3i + 2*0) + (3i + 2*1) + (3i + 2*2) = 9i + 6(3i + 2j) = ( 9i + 6) = 9 i + 6Now...