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If `|z-4/z|=2`, then the maximum value of`|Z|`is equal to(1) `sqrt(3)+""1`(2) `sqrt(5)+""1`(3) 2(4) `2""+sqrt(2)` |
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Answer» `|z| = |z-4/z + 4/z| ` `<= |z-4/z| + |4/z|` `|z| <= 2 + 4/|z| ` `=> |z| - 2 - 4/|z| <= 0` `(|z|^2 - 2|z| -4)/|z| <= 0 ` roots are `|z = +- 2 + - (sqrt(4 +16))/2` `= 1 +- sqrt5 ` `0 <= |z| <= 1 + sqrt5 ` max `|z| = 1 + sqrt(5 )` option2 is correct |
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