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If `cos x - y^(2) - sqrt(y - x ^(2) - 1 )ge 0 ` , thenA. ` y ge 1 `B. `x in ` RC. `y = 1 `D. `x = 0` |
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Answer» Correct Answer - 3,4 ` cos x- y^(2) - sqrt(y - x^(2) - 1 ) ge 0 ` (1) Now , `sqrt(y - x^(2) - 1)` is defined when ` y - x^(2) - 1 ge 0 or ge x^(2) + 1 ` so minimun values of y is 1. From (1), ` cos x - y^(2) ge sqrt(y - x^(2) - 1)` where `cos x - y^(2) ge 0 ` [ as when cos x is maximum `(=1) and y^(2) ` is minimum (=1), so cos x - `Y^(2)` is maximum ] . Also, ` sqrt(y - x ^(2) - 1)` Hence, `cos x - y^(2) = sqrt(y - x ^(2) - 1)= 0 ` `rArr y = 1 cos x = 1 , y = x^(2) = 1 ` `rArr x = 0, y = 1 ` |
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