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hi for this question
g:x- x/x-2 x>2

what is the range i am getting g(x)>3 ? correct or not thanks
not correct (assuming you meant x/(x-2) for x>2)
what happens when x gets very large?
(Original post by sputum)
not correct (assuming you meant x/(x-2) for x>2)
what happens when x gets very large?
the y value increases
(Original post by otrivine)
the y value increases
3/(3-2) = 3
4/(4-2) = 2
5/(5-2) = 5/3
the function value decreases as x increases.
(Original post by sputum)
3/(3-2) = 3
4/(4-2) = 2
5/(5-2) = 5/3
the function value decreases as x increases.
yes thats what i done but how would i convert it to the form of < > ??
(Original post by otrivine)
yes thats what i done but how would i convert it to the form of < > ??
try using bigger numbers for x values like 100, 1000 etc. What is the y value getting towards?
(Original post by otrivine)
yes thats what i done but how would i convert it to the form of < > ??
How did you get
g(x)>3
?

Basically you look at the ends. Values very near the minimum (2) and the maximum (squillions+)
so for some small bit over 2 (say 15/7) you get (15/7)/(1/7) = 15. You can get to any positive number by taking a point near enough to x=2.
As the difference between a squillion and (squillion-2) is tiny, dividing one by the other gets you very close to 1. Ever-closer with larger values of n.
So you can't get to one (because n-2 just doesn't equal n) but you can hit anything over 1 and as vast as you like.
(Original post by mr tim)
try using bigger numbers for x values like 100, 1000 etc. What is the y value getting towards?
look the values for x>2 then is like x=3,4,5 i can chose and when i sub in i get the values for y those are the ranges so then how can i convert it to <> thats what i want to know?
(Original post by sputum)
How did you get ?

Basically you look at the ends. Values very near the minimum (2) and the maximum (squillions+)
so for some small bit over 2 (say 15/7) you get (15/7)/(1/7) = 15. You can get to any positive number by taking a point near enough to x=2.
As the difference between a squillion and (squillion-2) is tiny, dividing one by the other gets you very close to 1. Ever-closer with larger values of n.
So you can't get to one (because n-2 just doesn't equal n) but you can hit anything over 1 and as vast as you like.

look the values for x>2 then is like x=3,4,5 i can chose and when i sub in i get the values for y those are the ranges so then how can i convert it to <> thats what i want to know?
When x is just over 2 e.g. 2.00000000001 what is the number like

When x is very big is there much difference between x and x-2 if there were no difference between them .... what number would you have
(Original post by otrivine)
look the values for x>2 then is like x=3,4,5 i can chose and when i sub in i get the values for y those are the ranges so then how can i convert it to <> thats what i want to know?
Well you can 'get' anywhere between 1 (excluding 1 itself as above) and as large a number as you can care to name (taking x as near to 2 as you like)
So the range of g(x) is >1 or (1,inf)
I don't know how this is taught at sixth form or how rigorous your answer needs to be.
(Original post by otrivine)
hi for this question
g:x- x/x-2 x>2

what is the range i am getting g(x)>3 ? correct or not thanks

Now it is easier to deduce the range.
(Original post by raheem94)

Now it is easier to deduce the range.
hi raheem how are you? ok my question is you know in the question they put x>2 right and that means i can chose any values greater than 2 like 3,4,5 and i sub in to equation and get the values and i will get the range values so which value should i use dont i use the one i sub in 3 to the equation cause that is the minimum value?many thanks
(Original post by otrivine)
hi raheem how are you? ok my question is you know in the question they put x>2 right and that means i can chose any values greater than 2 like 3,4,5 and i sub in to equation and get the values and i will get the range values so which value should i use dont i use the one i sub in 3 to the equation cause that is the minimum value?many thanks
remember you use values of x>2 and that includes all REAL numbers (ie: 2,3,4 as well as 2.0000000000001) and because its any number more than 2 you have to use bigger numbers too like 100, 1000 etc. Try to use smaller numbers and bigger numbers and see what range you get.
(Original post by otrivine)
hi raheem how are you? ok my question is you know in the question they put x>2 right and that means i can chose any values greater than 2 like 3,4,5 and i sub in to equation and get the values and i will get the range values so which value should i use dont i use the one i sub in 3 to the equation cause that is the minimum value?many thanks
I am fine.

The equation is

If we sub in x=3, we get, g(x)=3
If we sub in x=4 we get, g(x)=2
If we sub in x=5 we get, g(x) = 1.66666666666
...
If we sub in x=100 we get, g(x)=1.020408163
...
If we sub in x=1000 we get, g(x)=1.002004008
From above we can deduce that no value will be less than or equal to 1.

X=3 is not the minimum value for domain of x>2.

Now sub in x=2.01, we get, g(x)=201
...
Now sub in x=2.000001, we get, g(x)=2000001

This shows us that the range is g(x)>1.

Do you understand it now?
Last edited by raheem94; 16-04-2012 at 19:36.
(Original post by raheem94)
I am fine.

The equation is

If we sub in x=3, we get, g(x)=3
If we sub in x=4 we get, g(x)=2
If we sub in x=5 we get, g(x) = 1.66666666666
...
If we sub in x=100 we get, g(x)=1.020408163
...
If we sub in x=1000 we get, g(x)=1.002004008
From above we can deduce that no value will be less than or equal to 1.

X=3 is not the minimum value for domain of x>2.

Now sub in x=2.01, we get, g(x)=201
...
Now sub in x=2.000001, we get, g(x)=2000001

This shows us that the range is g(x)>1.

Do you understand it now?
so does it always have to be 1?
(Original post by otrivine)
so does it always have to be 1?
It can't equal 1, it will be greater than 1.
(Original post by raheem94)
It can't equal 1, it will be greater than 1.
yes so for any other equations should it always be greater than 1?
(Original post by otrivine)
yes so for any other equations should it always be greater than 1?
No, it depends upon the question.

e.g. Range of the function will be
(Original post by raheem94)
No, it depends upon the question.

e.g. Range of the function will be
thanks and how would u differentiate this
PEpower-KT ?