JEE Advanced2026MathematicsQuadratic EquationActual
Let a, b, c be positive integers in arithmetic progression such that the equation ax^2 + bx + c = 0 has only integer solutions. Then which of the following statements is (are) TRUE ?
Options
- Ac - b is an integer multiple of a
- BBoth the roots of the equation ax^2 + bx + c = 0 are odd integers
- CIf c = 15 , then ab = 8
- DIf b = 8 , then x = 3 is a root of the equation ax^2 + bx + c = 0
Correct answer
A. c - b is an integer multiple of a
Step-by-step solution
Given a, b, c are in arithmetic progression, we have 2b = a + c . Let the integer roots of the equation ax^2 + bx + c = 0 be and . Sum of the roots is + = - b a and product of the roots is = c a . Dividing the arithmetic progression condition by a , we get: 2b a = 1 + c a Substituting the sum and product of the roots: -2( + ) = 1 + + 2 + 2 + 1 = 0 Adding 3 to both sides to factorize: + 2 + 2 + 4 = 3 ( + 2)( + 2) = 3 Since and are integers, ( + 2) and ( + 2) must be integer factors of 3 . The possible pairs are (1,