For correct results it should be modified to
xy+1 = (3k+1)(9m+8)+1
= 27km+24k+9m+9 which is divisible by 3.
Although here the answer is the same, you should not use k in both the equations.
. If x and y are integers, is xy + 1 divisible by 3?
(1) When x is divided by 3, the remainder is 1.
(2) When y is divided by 9, the remainder is 8.
(3k+1)(9k+8)+1=60k+9 therefore it is divisible by 3 (c)
is my way right? or is there any better way to solve such questions???
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