1.

If `alpha, beta` are the roots of `px^(2) + qx + r = 0`, then `alpha^(3) + beta^(3) = "______"`.A. `(3qpr-q^(3))/(p^(3))`B. `(3pqr-3q)/(p^(3))`C. `(pqr - 3q)/(p^(3))`D. `(3pqr -q)/(p^(3))`

Answer» Correct Answer - A
`alpha + beta = (-q)/(r )`
`alpha.beta = (r )/(p)`
`alpha. Beta = r/p`
`alpha^(3) + beta^(3) = (alpha + beta)^(3) - 3alpha beta (alpha + beta)`
`= ((-q)/(p))^(3)- 3(r/p) (-q/p)`
`= (-q^(3) + 3 pqr)/(p^(3))`
`:. alpha^(3) + beta^(5) = (3pqr - q^(3))/(p^(3))`.


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