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If a and b are positive real numbers other than unity, then the least value of `|"log"_(b) a + "log"_(a) b|`, is |
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Answer» Correct Answer - C We have, `|"log"_(b) a + "log"_(a)b|` `=|"log"_(b)a +(1)/("log"_(b)a)| = |x + (1)/(x)|, "where " x = "log"_(b)a,` We know that `x+ (1)/(x) ge 2 " for all" x gt 0 " and ", x + (1)/(x) le -2 " for all" x lt 0` `therefore |x + (1)/(x)| ge 2 " for all" x ne0` `therefore |"log"_(b)a + "log"_(a)b| ge 2` Hence, the least value of `|"log"_(b)a + "log"_(a)b|` is 2. |
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