The inequality `sqrt(x^((log)_2sqrt(x)))geq2` is satisfied by only one value of `x` (b) `x in ((0,1)/4)` `x in [4,oo)` (d) `x in (1,2)`
The inequality `sqrt(x^((log)_2sqrt(x)))geq2`
is satisfied by
only one value of `x`
(b) `x in ((0,1)/4)`
`x in [4,oo)`
(d) `x in (1,2)`
A. only one value of x
B. ` x in (0, 1/4]`
C. ` x in [4, infty)`
D. ` x in (1, 2)`
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Correct Answer - B::C
` sqrt(x^(log_(2)sqrtx))ge 2, x gt 0`
` rArr x^(log_(2)sqrtx) ge 4`
Taking log on both sides with base 2, we get
` log_(2)x^(log_(2)sqrtx)ge 2`
` or (log_(2)sqrtx)(log_(2) x) ge 2`
` or (1//2)(log_(2)x)(log_(2)x) ge 2`
` or (log_(2)x)^(2) ge 4`
` or (log_(2)x-2)(log_(2)x+2) ge 0`
` rArr log_(2)x le - 2 or log_(2)x ge 2`
` rArr x le 1//4 or x ge 4`
` rArr x in (0, 1//4] cup [4, infty)`
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