1.

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))`

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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