What is the square root of 256.25 ?

Question

3341 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-12-17T18:51:26

#sqrt(256*25) = 80#

#sqrt(256.25) ~~ 16.00781#

Let's look at both possibilities:

#color(white)()#
Square root of #256*25#

If there is a typo in the question and the decimal point was meant to signify multiplication then we find:

#sqrt(256*25) = sqrt(16^2*5^2) = sqrt(16^2)*sqrt(5^2) = 16*5 = 80#

#color(white)()#
Square root of #256.25#

If the question is correct as stands, then we cannot simplify the square root, but we can approximate it.

Note that #4*256.25 = 1025 = 32^2+1#

Since this is of the form #n^2+1# its square root is expressible as very regular continued fraction:

#sqrt(1025) = [32;bar(64)] = 32+1/(64+1/(64+1/(64+1/(64+...))))#

Hence:

#sqrt(256.25) = 1/2 sqrt(1025) = 1/2 [32;bar(64)]#

We can truncate the continued fraction to get approximations.

For example:

#sqrt(256.25) ~~ 1/2 [32,64] = 1/2 (32+1/64) = 16+1/128 = 16.0078125 ~~ 16.00781#