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Question

Question: The least value of the expression 2log<sub>10</sub>x – log<sub>x</sub>(0.01), for x \> 1, is-...

The least value of the expression

2log10x – logx(0.01), for x > 1, is-

A

10

B

2

C

–0.01

D

None of these

Answer

None of these

Explanation

Solution

logx.01 = –2 logx10

Thus expression = 2 [log10x + logx10]

= 2 [log10x+1log10x]\left\lbrack \log_{10}x + \frac{1}{\log_{10}x} \right\rbrack

Put log10x = 1

But x + 1x\frac{1}{x} ³ 2 if x > 0 and x + 1x\frac{1}{x} £ –2 if x < 0 least value of

expression = 4 because

log10x < 0 " x > 1

So correct choice is