1.

A quadratic equation with integral coefficients has two different primenumbers as its roots. If the sum of the coefficients of the equation isprime, then the sum of the roots is`2`b. `5`c. `7`d. `11`A. 2B. 5C. 7D. 11

Answer» Correct Answer - 2
Let equation is `a (x - alpha) (x - beta) = 0`, where `alpha, beta` are prime numbers
Sum of coefficients `= a - a(alpha + beta) + aalphabeta`
`= a(alpha - 1) (beta - 1)`, which is prime number
`rArr a = 1` and one of `(alpha - 1) and (beta - 1)` will be 1
Let `alpha - 1 = 1` or `alpha = 2`.
then `beta - 1` will be 2.
So `beta = 3`
Hence, sum of roots = 5


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