Question

Let Z denotes the set of all integers and A = {(a, b): a2 + 3b2 = 28. a,b ∈ Z} and B ={(a, b):a < b,a,b ∈ Z}. Then, the number of elements in A ∩ B is

(a) 2

(b) 4

(c) 6

(d) 5

Answer 1

Correct Option: (c)

Explanation:

Similarly by putting the values of a we can find the values of b.

=> A = {(5, 1), (-5, -1), (5, -1), (-5, 1), (4, 2), (-4, -2),(4, -2), (-4, 2), (1, 3), (-1, -3), (1,-3),(-1, 3)}

Also we have,