Discussion Forum

If x and y are positive integers such that (3x + 7y) is a multiple of 11, then which of the following will also be divisible by 11 ?

Answer:

Explanation:

By hit and trial method, we get x=5 and y=1 such that 3x + 7y = 15 + 7 = 22 is a multiple of 11.

Then

(4x + 6y) = (4 × 5 + 6 × 1) = 26 which is not divisible by 11

(x + y + 4) = (5 + 1 + 4) = 10 which is not divisible by 11

(9x + 4y) = (9 × 5 + 4 × 1) = 49 which is not divisible by 11

(4x - 9y) = (4 × 5 - 9 × 1) = 20 - 9 = 11 which is divisible by 11