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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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