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If two roots of the equation `x^3-px^2+qx-r=0` are equal in magnitude but opposite in sign, then:A. r = pqB. `r = 2p^(3) + pq`C. `r = p^(2)q`D. none of these

Answer» Correct Answer - A
Let `alpha, beta, gamma` be the roots of the given equation such that `alpha = - beta`. Then, `alpha + beta + gamma = p rArr gamma = p`.
Since `gamma` is a root of the given equation, so it satisfies the equation i.e. `gamma^(3) - p gamma^(2) + q gamma - r = 0 rArr p^(3) - p^(3) + pq - r = 0 rArr r = pq`


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