The number of positive integral solutions of x1x2x3x4=770 is

x1x2x3x4=770=2×5×7×11We can assign 2 to any one of xi s . Thus 2 can be assigned in 4 ways similarly each of 5, 7, 11 can beassigned in 4 ways.the number of positive integer solutions = 4 x 4 x4x 4 =256