AP EAMCET202119 Aug 2021Morning ShiftMathematicsSequences and SeriesActual
Let f ( x ) = x 3 + a x 2 + b x + c be polynomial with integer coefficients. If the roots of f ( x ) are integer and are in Arithmetic Progression, then ' a ' cannot take the value
Options
- A− 642
- B1214
- C1323
- D1626
Correct answer
B. 1214
Step-by-step solution
Given that, f ( x ) = x 3 + a x 2 + b x + c Now, since the roots of the polynomial are in Arithmetic Progression, Let the roots are s - t ,   s ,   s + t ⇒ s - t + s + s + t = - a 1 ⇒ - 3 s = a Hence, a must be multiple of 3 . From given options we see that only 1214 is not multiple of 3 .