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Need help with c2 questions

1)Does anyone know how to draw the graph y=x+(3/x)? What does the x do ?? 2) how do you sketch this? Y=(x+k)^2-9,k>0 thanks for the help I am really stuck
(edited 8 years ago)
Reply 1
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coconut64
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Also could anyone explain this? IMAG0064.jpg f3 I don't get which length I am supposed this find and I did this
Attachment not found
IMAG0065.jpg349.5KB
y=(x+3)/x is the same as y=3/x +1
Original post by coconut64
1)Does anyone know how to draw the graph y=x+3/x? What does the x do ?? 2) how do you sketch this? Y=(x+k)^2-9,k>0 thanks for the help I am really stuck


For your first question, you may wish to plug in numbers that give you nice outputs like x = 1, x = 0.5 etc and see if you can spot the shape, which is similar to 1/x.

For your second question, think about the different distinct points on the graph (Where is the maximum/minimum, when is y =0, when is x =0?) and think about how that helps.
(edited 8 years ago)
Reply 4
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kkboyk
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Original post by coconut64
1)Does anyone know how to draw the graph y=x+3/x? What does the x do ?? 2) how do you sketch this? Y=(x+k)^2-9,k>0 thanks for the help I am really stuck


Y = (x+3)/x is the same as y = 1 + 3/x (so is a translation. At this point consider Y = 3/x and draw the graph, what would happen if we add 1)

The second queation is basically the same except with have k being added to x. First consider Y = x^2 -9 and plot this graph Using the interval [-3,3], what would happen if we add a number k to x? Try making k equals 2 and do the same thing as before, and compare both answers.
(edited 8 years ago)
Reply 5
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coconut64
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Original post by whydoidothis?
y=(x+3)/x is the same as y=3/x +1


No I mean y=x+(3/x), thanks
(edited 8 years ago)
find the intercepts then sketch the graph (pay careful attention to the function transformations to make sure you get the positions right). also to find the length of the tangents, just use Pythagoras' theorem.
(edited 8 years ago)
Reply 7
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coconut64
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Original post by kkboyk
Y = (x+3)/x is the same as y = 1 + 3/x (so is a translation. At this point consider Y = 3/x and draw the graph, what would happen if we add 1)

The second queation is basically the same except with have k being added to x. First consider Y = x^2 -9 and plot this graph Using the interval [-3,3], what would happen if we add a number k to x? Try making k equals 2 and do the same thing as before, and compare both answers.

Hi, it is x+(3/x )thanksr
(edited 8 years ago)
Reply 8
Avatar for ombtom
ombtom
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Original post by coconut64
Hi, it is x+(3+x)/x thanks


Is it y=x+3/x y = x + 3/x or y=x+(3+x)/x y = x + (3+x)/x ? You have said both.
Reply 9
Avatar for kkboyk
kkboyk
21
Original post by ombtom
Is it y=x+3/x y = x + 3/x or y=x+(3+x)/x y = x + (3+x)/x ? You have said both.


This has just got confusing :biggrin:
Reply 10
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ombtom
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Original post by kkboyk
This has just got confusing :biggrin:


I initially thought it was y=(x+3)/x y = (x+3)/x :redface:
Reply 11
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coconut64
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Original post by ombtom
Is it y=x+3/x y = x + 3/x or y=x+(3+x)/x y = x + (3+x)/x ? You have said both.


Sorry, I just realise it is y=x+(3/x)
(edited 8 years ago)
Reply 12
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coconut64
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Original post by ombtom
I initially thought it was y=(x+3)/x y = (x+3)/x :redface:


Sorry guys it is actually y=x+(3/X)
Reply 13
Avatar for kkboyk
kkboyk
21
Original post by coconut64
Sorry, I just realise it is y=x+(3)/x


Try drawing y=x and y=3/x separate on the same graph to help you visualise
Reply 14
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coconut64
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Original post by kkboyk
Y = (x+3)/x is the same as y = 1 + 3/x (so is a translation. At this point consider Y = 3/x and draw the graph, what would happen if we add 1)

The second queation is basically the same except with have k being added to x. First consider Y = x^2 -9 and plot this graph Using the interval [-3,3], what would happen if we add a number k to x? Try making k equals 2 and do the same thing as before, and compare both answers.

Why doyou make k =2?
Reply 15
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coconut64
OP
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Original post by SeanFM
For your first question, you may wish to plug in numbers that give you nice outputs like x = 1, x = 0.5 etc and see if you can spot the shape, which is similar to 1/x.

For your second question, think about the different distinct points on the graph (Where is the maximum/minimum, when is y =0, when is x =0?) and think about how that helps.

Thanks for the reply but how do you work out k?
Reply 16
Avatar for kkboyk
kkboyk
21
Original post by coconut64
Why doyou make k =2?


Just to make you visualise what would happen for any values of k (it will translate to the left for every positive value of K)
Original post by coconut64
Thanks for the reply but how do you work out k?


You don't - k is any positive number in this case (it says k>0) so it wants you to have things in terms of k.

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