Forums

We want to share an important update with our Betfair Community users.

Over the coming months, the Betfair Community platform will be winding down. The final active day for the platform will be December 21st. From December 22nd, users will no longer be able to access the platform.

Your discussions, insights, engagement, and, most importantly, feedback have helped shape the platform and guided innovation. Your feedback continues to be important to us, and we will continue to listen via our dedicated feedback channels, as well as through product testing and innovations.

To share your feedback and experience, visit: https://support.betfair.com/app/home

Welcome to Live View – Take the tour to learn more
Start Tour
There is currently 1 person viewing this thread.
Twoboyz
14 Sep 15 10:36
Joined:
Date Joined: 19 Feb 03
| Topic/replies: 4,436 | Blogger: Twoboyz's blog
(9 / ?)Square root 3 = -27

What is the correct method to work it out please?
Pause • Switch to Standard View Maths question
Show More
Loading...
Report rob_dylan • September 14, 2015 10:44 AM BST
(9/x)root3 = -27  is that the equation. 

REckon x = root3 over three then.

9root3 = -27x  (multiply both sides by x)

-(9root3 over 27) = x   (divide both sides by -27)

-root3/3  = x  (divide top and bottom of left side by 9)
Report xmoneyx • September 14, 2015 10:47 AM BST
Crazy
Report Pleasegivemeanailedontip • September 14, 2015 1:15 PM BST
Is it 27?

If the first bracket was 3 youd get 27 so does that mean getting -3 in the first bracket (9/27) gets minus 27?
Report brendanuk1 • September 14, 2015 2:01 PM BST
doesnt minus 27 fook things up with imaginary numbers Confused
Report Doctor Feelgood • September 14, 2015 2:22 PM BST
? = -0.577350269189626
Report screaming from beneaththewaves • September 14, 2015 2:28 PM BST
What does square root3 mean? 3 times the square root of the number in the bracket? The cube root of the number in the bracket?
Report Foinavon • September 14, 2015 3:41 PM BST
Brendan is right, the square root of a negative number has an i component.
The square root of a positive number has two solutions, one positive, the other negative.
Report dunlaying • September 14, 2015 3:47 PM BST
I am rusty but perhaps cross multiplying to get

(9sqrt3)/(-27)=x=-sqrt3^-1
Report zorrostrikes • September 14, 2015 3:49 PM BST
-3  ?
Report Foinavon • September 14, 2015 4:01 PM BST
(9sqrt3)/(-27)=x simplifies to -sqrt3/3 = x (Rob Dylan's solution)

This is - sqrt(+3)/3 =x so is not imaginary and has two solutions positive and negative rendering the inital negative superfluous.
Report brendanuk1 • September 14, 2015 4:10 PM BST
I read it as cube root, not 'multiply by sqrt of 3'
Report dunlaying • September 14, 2015 4:12 PM BST
- sqrt3^-1
Report Foinavon • September 14, 2015 4:34 PM BST
Sorry, don't know where you get that from dunlaying.
Report dunlaying • September 14, 2015 4:40 PM BST
I have probably been clumsy as Rob Dylan has written it -sgrt3/(3).
If you cross multiply and cancel you will see that the answer is negative, I hope.
Report Foinavon • September 14, 2015 4:47 PM BST
Yes, -sqrt3 =3x
sqrt3 = 1.732 and -1.732
as does -sqrt3

(hope that's right)
Report mememe • September 14, 2015 4:58 PM BST
(9/x) multiplied by sq rt 3 = -27
(9/x) multi by 1.73 = -27
divide both sides by 1.73
9/x = -27/1.73
9/x = -15.61
multi both sides by x
9 = -15.61x
9/-15.61 = x
-0.58 = x

Happy

(I think)
Report Foinavon • September 14, 2015 6:14 PM BST
x = -0.58 and +0.58 (see my previous post)
Report Magnusthepassenger • September 14, 2015 7:05 PM BST
9/x × √3 = -27
9√3 = -27x
(9√3)/(-27) = x
X =-0.577 or 0.577

As Foinavon points out, the square root of 3 has two values, 1.732 and - 1.732
Report dunlaying • September 14, 2015 7:31 PM BST
Of course a square root can be positive or negative but in this case the answer is negative.
Take the original equation and you have a positive multiplied by an unknown equal to a negative. Since a positive multiplied by a positive is positive it follows that the unknown be negative.
Report Magnusthepassenger • September 14, 2015 7:46 PM BST
Dunlaying you are correct. To get the negative answer the unknown must be negative (-0.577)
Report Foinavon • September 14, 2015 8:03 PM BST
Which part of the LHS is positive? Both 9/x and sqrt3 can be either. If one is +ve the other is -ve.
Report Foinavon • September 14, 2015 8:15 PM BST
To clarify
if 9/x is positive, sqrt 3 is negative.
if 9/x is negative, sqrt 3 is positive.

x is both + 0.577 and -0.577
Report Darlo Bantam • September 14, 2015 9:12 PM BST
Answer is -[3 / (sqrt 3)]
Report screaming from beneaththewaves • September 14, 2015 9:27 PM BST
x = the square root of 3, divided by minus 3

If the square root is taken to be the positive one, then x is a positive divided by a negative, which is a negative number.

If the square root is taken to be the negative one, then s is a negative divided by a negative, which is a positive number.

So x has two values, a positive one and a negative one.

I agree with Foinavon imo.
Report boxingthefox • September 14, 2015 9:31 PM BST
What is the square root of 69...............it's ate something...........hold on it's ate.30662386291





I'll get me coat
Report Petrus Romanus • September 14, 2015 10:33 PM BST
Here's how I would do it...might be a bit more long winded but its how I was taught

(9 / ?)Square root 3 = -27 ....the problem

(9/x)(√3) = -27 ...............next move substitute √3 (which is 1.73)
(9/x)(1.73) = -27...............next move is to get the x fraction isolated on one side of the equal sign

9/x = -27/1.73..............next step cross multiply to get rid of fractions (multiply -27 by x and multiply 9 by 1.73)

-27x = 15.57...............next divide both sides by -27 to find x

x = 15.57/-27................calculator time

x = -0.57................answer (plus the Foinavon thisg above...can also be a positive value 0.57)
Report dunlaying • September 15, 2015 7:51 PM BST
Go back to basics and you will find that a number divided by a fraction is the same as that number multiplied by the reciprocal of the fraction eg (2x3) divided by (1/2) =6x(2/1) =12 , x being the multiplication sign.
If you substitute the two answers in our original question you find that -(sqrt3)^-1 gives -27 on the left hand side and -27 on the right hand side which is an equation.
If, however, we substitute +(sqrt3)^-1 in our original question we find that the LHS reads as +27 and the RHS as -27 which is not an equation.
Post Your Reply
<CTRL+Enter> to submit
Please login to post a reply.

Wonder

Instance ID: 13539
www.betfair.com