IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: IO4567 on April 27, 2010, 06:40:19 pm
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Please could anyone help me here - I'm blank.
x2 + 2xy - 3y2 + 16 = 0
Find the coordinates of the points on the curve where dy/dx = 0.
I've done the differentiation correctly (I think) and got this:
-2x -2y
______ = 0
2x - 6y
But now I have no idea what to do to get the coordinates! Someone please help!
In the markscheme it says 'Eliminating either variable and solving for at least one value of x or y'.
How do I 'eliminate either variable'?
Thank you so much!
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Please could anyone help me here - I'm blank.
x2 + 2xy - 3y2 + 16 = 0
Find the coordinates of the points on the curve where dy/dx = 0.
I've done the differentiation correctly (I think) and got this:
-2x -2y
______ = 0
2x - 6y
But now I have no idea what to do to get the coordinates! Someone please help!
In the markscheme it says 'Eliminating either variable and solving for at least one value of x or y'.
How do I 'eliminate either variable'?
Thank you so much!
Yuo u got the diff right..
now.u equte the numerator to zero..as its not possible to have a zero denominator:
-2x-2y=0
2x=-2y
x=-y
then substitute x in the original equation with -y...try it and tell me :)
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ok look dude when dy/dx=0 this means ur differentiation should be 0 i have done my differentiation as (2x+2y)/(-2x+6y) now throw the denominator away cuz u cnt divide anything by 0 and then take the nominator =0 as for the differentiantion to be 0 nomintor should be 0
soz 2x+2y=0 get the x to 0 or y to 0 and substitute in the equation final answer should be (0,sq root 16/3) (0,-sq root 16/3)
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wow! thank you guys so much! really appreciate the help! cheers