
Case 1 : a,b are co prime HCF = 1
a + b + ab = 89
a + b + ab + 1 = 90
(a + 1)(b + 1) = 90 = 2 * 3^2 * 5
No of factors = 12
Solutions 12/2  1 = 5; a cannot be 0
Case 2 : HCF>1 Let it be h
h(a + b + ab/h^2) = 89
h cannot be 1 and 89 is prime.
No solutions
