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If one of the roots of `ax^(2) + bx + c = 0` is thrice that of the other root, then b can beA. `(4ac)/(3)`B. `(16ac)/(9)`C. `4sqrt((ac)/(3))`D. `sqrt((4ac)/(3))` |
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Answer» Correct Answer - C Let the roots be k and 3k. Sum of the roots `= k + 3 k`. `rArr 4 k = (-b)/(a) rArr k = (-b)/(4a)`. Product of the roots `= k xx 3 k` `rArr 3k^(2) = c/a` `rArr 3((-b)/(4a))^(2) = c/a` `rArr (3b^(2))/(16a^(2)) = c/a` `rArr 3b^(2) = 16 ac` `rArr b = +-sqrt((ac)/(3))`. |
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