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If `alpha,beta` are the roots of `ax^2 + c = bx`, then the equation `(a + cy)^2 =b^2y` in y has the rootsA. `alpha beta^(-1), alpha^(-1)beta`B. `alpha^(-2), beta_(-2)`C. `alpha^(-1), beta^(-1)`D. `alpha^(2), beta^(2)` |
Answer» Correct Answer - 2 `ax^(2) - bx + c = 0` `alpha + beta = b/a, abeta = c/a` Also, `(a + cy)^(2) = b^(2)y` `rArr c^(2)y^(2) - (b^(2) - 2ac)y + a^(2) = 0` `rArr (c/a)^(2)y^(2) - ((b/a)^(2) - 2(c/a))y + 1 = 0` `rArr (alphabeta)^(2)y^(2) - (alpha^(2) + beta^(2))y + 1 = 0` `rArr y^(2) - (alpha^(-2) + beta^(-2))y + alpha^(-2)beta^(-2) = 0` `rArr (y - alpha^(-2)) (y - beta^(-2)) = 0` Hence, the roots are `alpha^(-2), beta^(-2)`. |
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