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If the sum of the roots of an equation is 2 and the sum of their cubesis 98, then find the equation. |
Answer» Correct Answer - `x^(2) - 2x - 15 = 0` Let the roots be ` alpha and beta ` . Then , ` alpha + beta = 2 and alpha^(3) + beta^(3) = 98` Now, ` alpha^(3) + beta^(3) = (alpha + beta ) (alpha^(2) - alpha beta + beta^(2))` `rArr 98 = 2 [(alpha + beta)^(2) - 3alpha beta]` or ` 49 = (4 - 3 alpha beta)` or ` alpha beta = - 15` Thus, the equation is `x^(2) - 2x - 15 = 0` |
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