How many pairs of natural numbers are there the difference of whose squares is 45?
a)0 b)1 c) 2 d) 3 e) none of these
a)0 b)1 c) 2 d) 3 e) none of these
a^2 -b^2 = 45gmatmachoman wrote:How many pairs of natural numbers are there the difference of whose squares is 45?
a)0 b)1 c) 2 d) 3 e) none of these
(a+b)(a-b) = 45
45 = 45*1 or 9*5 or 15*3
if a+b =45
and a-b = 1
a = 23 and b = 22
if a+b = 9
and a-b = 5
a = 7 and b = 2
if a+b =15 and
a-b = 3
a= 9 and b = 6
So there are clearly 3 pairs of natural numbers which satisfy this
