Question

find square root 92.4 using log table ?? plz help me..​

Answer 1

Answer:

I don't know anything about whether you get log tables or not in ICSE exams. I'm a lowly CBSE kid. But I can tell you how to find square roots using log tables.

Take the number you want and find its log.

Multiply the value of the log by 0.5(0.5( halve it)

Take the antilog of the value so obtained.

Justification: Let xx be the number whose square root is desired.

Then,

x−−√=x12x=x12

Taking logs,

log(x−−√)=log(x12)log⁡(x)=log⁡(x12)

Using, logan=nloga,log⁡an=nlog⁡a,

log(x−−√)=12logxlog⁡(x)=12log⁡x

Therefore,

x−−√=antilog(0.5logx)x=antilog(0.5log⁡x)

This is actually a great trick for saving time. If only CBSE gave us log tables.

In case you are unfamiliar with using log tables