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(9 / ?)Square root 3 = -27
What is the correct method to work it out please?
What is the correct method to work it out please?
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(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) |
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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? |
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doesnt minus 27 fook things up with imaginary numbers
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? = -0.577350269189626
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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?
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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. |
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I am rusty but perhaps cross multiplying to get
(9sqrt3)/(-27)=x=-sqrt3^-1 |
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-3 ?
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(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. |
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I read it as cube root, not 'multiply by sqrt of 3'
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- sqrt3^-1
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Sorry, don't know where you get that from dunlaying.
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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. |
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Yes, -sqrt3 =3x
sqrt3 = 1.732 and -1.732 as does -sqrt3 (hope that's right) |
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(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  (I think) |
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x = -0.58 and +0.58 (see my previous post)
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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 |
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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. |
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Dunlaying you are correct. To get the negative answer the unknown must be negative (-0.577)
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Which part of the LHS is positive? Both 9/x and sqrt3 can be either. If one is +ve the other is -ve.
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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 |
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Answer is -[3 / (sqrt 3)]
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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. |
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What is the square root of 69...............it's ate something...........hold on it's ate.30662386291
I'll get me coat |
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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) |
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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. |