How do you find the square root of 270?

3 Answers
Apr 29, 2017

See the solution process below:

Explanation:

We can use this rule of radicals to rewrite this expression:

sqrt(a * b) = sqrt(a) * sqrt(b)ab=ab

sqrt(270) = sqrt(9 * 30) = sqrt(9) * sqrt(30) = +-3sqrt(30)270=930=930=±330

If necessary, the sqrt(30) = +-5.47730=±5.477

And therefore:

+-3sqrt(30) = +-3 *+- 5.477 = +-16.432±330=±3±5.477=±16.432 rounded to the nearest thousandth.

Apr 30, 2017

A = 3 * sqrt30330

Explanation:

Find a sqrt which can be divided by the whole number:
= sqrt3030

Then find the quotient of the number and the divisor (sqrt):
= 270 / sqrt3030
= 3
= 3 * sqrt3030

Apr 30, 2017

sqrt(270) = 3sqrt(30) ~~ 15873/966 ~~ 16.431677270=3301587396616.431677

Explanation:

First note that 270270, like any positive number, has two square roots. We denote the positive square root by sqrt(270)270 and the negative one by -sqrt(270)270. However, the expression "the square root" is often used to refer to the principal, positive square root.

Next note that if a, b >= 0a,b0 then:

sqrt(ab) = sqrt(a)sqrt(b)ab=ab

[[ The same is not true if both a < 0a<0 and b < 0b<0 ]]

Also, if a >= 0a0 then:

sqrt(a^2) = aa2=a

So we find:

sqrt(270) = sqrt(9*30) = sqrt(9)sqrt(30) = 3sqrt(30)270=930=930=330

This is the simplest form of the principal square root.

3sqrt(30)330, like sqrt(30)30 is an irrational number.

We can calculate approximations to sqrt(30)30 using its continued fraction. Note that 30=5*630=56 is of the form n(n+1)n(n+1). Hence its square root has a short regular repeating pattern:

sqrt(30) = [5;bar(2,10)] = 5+1/(2+1/(10+1/(2+1/(10+1/(2+1/(10+...))))))

[[ In general sqrt(n(n+1)) = [n;bar(2,2n)] ]]

We can get decent approximations for sqrt(30) by truncating just before one of the 10's as follows:

sqrt(30) ~~ 5+1/2 = 11/2

sqrt(30) ~~ 5+1/(2+1/(10+1/2)) = 241/44

sqrt(30) ~~ 5+1/(2+1/(10+1/(2+1/(10+1/2)))) = 5291/966

Let's stop there and use this to give us an approximation for sqrt(270)...

sqrt(270) = 3sqrt(30) ~~ 3*5291/966 = 15873/966 ~~ 16.431677