How do you find a one-decimal place approximation for sqrt 3737?

1 Answer
Oct 18, 2015

Use one step of Newton Raphson method to find:

sqrt(37) ~~ 73/12 = 6.08dot(3) ~~ 6.1377312=6.08.36.1

Explanation:

To find the square root of a number nn, choose a reasonable first approximation a_0a0 and use the formula:

a_(i+1) = (a_i^2+n)/(2a_i)ai+1=a2i+n2ai

Repeat to get more accuracy.

For our purposes, n = 37n=37 and let a_0 = 6a0=6 since 6^2=3662=36.

Then:

a_1 = (a_0^2+n)/(2a_0) = (6^2+37)/(2*6) = (36+37)/12 = 73/12 = 6.08dot(3)a1=a20+n2a0=62+3726=36+3712=7312=6.08.3

We don't need any more steps to get the first decimal place, since we were pretty close to start.

Actually sqrt(37)37 is expressible as something called a continued fraction:

sqrt(37) = [6;bar(12)] = 6+1/(12+1/(12+1/(12+...)))

So you can also get approximations for sqrt(37) by just truncating this continued fraction and working out the value.

For example:

sqrt(37) ~~ [6;12,12] = 6+1/(12+1/12) = 6 + 12/145 = 882/145 ~~ 6.08276