is divisible by
- (A)34 but not by 14✓ Correct
- (B)both 14 and 34
- (C)neither 14 nor 34
- (D)14 but not by 34
Answer: (A)
Solution
Group the terms as . Since is divisible by and , each bracket is divisible by , so the whole expression is divisible by . The parity is oddoddeveneven, which is even, so the expression is also divisible by , and hence by .
For , work modulo : . With and , , so the expression . It is not divisible by , hence not by .
Therefore the expression is divisible by but not by .
For , work modulo : . With and , , so the expression . It is not divisible by , hence not by .
Therefore the expression is divisible by but not by .
JEE Main · 2023 · 08 Apr 2023 · Shift 2 · Single correct option