2x^2=4xy what is X/Y?
I know you normally can't divide by a variable unless you know its not ZERO but in this case the question is asking for a ratio of X/Y or a re-arrangement of the expression. Is it ok to divide XY on both side? (You can solve it both ways and its the same answer.) Just wonder about the fundamentals.
Basic Algebra
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- rishab1988
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2x^2-4xy=0
x(2x-4y)=0
x=0 or x=2y
x/y =2 [ x cannot be 0 for its a ratio]
This is like question giving you a quadratic equation involving distance and speed.Let x =distance and y=speed and asking you the time.Speed =0 means you never traveled [infinite here means that he will never complete the travel].
Tho I doubt that this is a GMAT question.Unless this is a P.S,I wont do this.On DS it would produce 2 answers.one answer would say it never moved[the object].The other would say it did.
More appropriately GMAT would test +ve and -ves in such questions.
x(2x-4y)=0
x=0 or x=2y
x/y =2 [ x cannot be 0 for its a ratio]
This is like question giving you a quadratic equation involving distance and speed.Let x =distance and y=speed and asking you the time.Speed =0 means you never traveled [infinite here means that he will never complete the travel].
Tho I doubt that this is a GMAT question.Unless this is a P.S,I wont do this.On DS it would produce 2 answers.one answer would say it never moved[the object].The other would say it did.
More appropriately GMAT would test +ve and -ves in such questions.
- jaymw
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Im just as curious as rishab1988 about where you got that question from.
There really are two answers to this problem.
First, assume x is not zero.
You want to know the value for x/y so solve for x/y and not for anything else.
2x^2=4xy |divide by x (you can do it here under the above assumption)
2x=4y | divide by 2y (y cannot be zero here, because the question probably wouldn't ask for the value of an undefined fraction)
2x/2y=2
x/y=2
So your first solution for the fraction x/y is 2.
However, assume x = 0.
2(0)^2=4*0*y will always be true
Therefore, if x is zero, x/y will also be zero!
Again, please tell me where you found this question!
There really are two answers to this problem.
First, assume x is not zero.
You want to know the value for x/y so solve for x/y and not for anything else.
2x^2=4xy |divide by x (you can do it here under the above assumption)
2x=4y | divide by 2y (y cannot be zero here, because the question probably wouldn't ask for the value of an undefined fraction)
2x/2y=2
x/y=2
So your first solution for the fraction x/y is 2.
However, assume x = 0.
2(0)^2=4*0*y will always be true
Therefore, if x is zero, x/y will also be zero!
Again, please tell me where you found this question!