Rudeboy999
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how to find the minimum point of a curve. I know you have to complete the square but i dont understand how you find the minimum points.

E.g. x² - 8x + 23 = (x-a)² + b
(x-4)² + 7 = 0

so what would the minimum points be and how would you work it out
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jklmn
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Find the second derivitive, and the higher value is the min
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Rudeboy999
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can you give a gcse answer plss
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M_E_X
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(Original post by Rudeboy999)
how to find the minimum point of a curve. I know you have to complete the square but i dont understand how you find the minimum points.

E.g. x² - 8x + 23 = (x-a)² + b
(x-4)² + 7 = 0

so what would the minimum points be and how would you work it out
The minimum point will be when x = -4. You have to set the inside of the bracket to zero.

Sub x= -4 in to the original equation to find the value of the function at this point.

source: http://www.mathcentre.ac.uk/resource...ingsquare1.pdf (section 4)
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jklmn
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You don't need to know that at gcse???
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englishman129
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differentiate it and then put in 'o' as the dy/dx.
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M_E_X
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(Original post by jklmn)
You don't need to know that at gcse???
(Original post by englishman129)
differentiate it and then put in 'o' as the dy/dx.
He is a GCSE student. Calculus is obviously not part of the GCSE syllabus. Stop trying to look clever guys - you're just looking like idiots by not reading the original question.
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englishman129
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okay, sorry - i'm doing GCSE Additional maths - where calculus is REQUIRED, i've never done it in normal maths. So u do diffrentiate.
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jonny23563
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(Original post by englishman129)
okay, sorry - i'm doing GCSE Additional maths - where calculus is REQUIRED, i've never done it in normal maths. So u do diffrentiate.
Differentiate, set this equal to 0 to find stationary points.

Check values either side of any stationary points to see whether they are minimum or maximum
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englishman129
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(Original post by jonny23563)
Differentiate, set this equal to 0 to find stationary points.

Check values either side of any stationary points to see whether they are minimum or maximum
exactly.
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assmaster
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(Original post by englishman129)
okay, sorry - i'm doing GCSE Additional maths - where calculus is REQUIRED, i've never done it in normal maths. So u do diffrentiate.
For this question, you can get the answer much more easily without calculus (although it would work too, it's just waaay longer)

It helps to imagine the curve, and the lowest point on that curve will be y=7 (due to the translation of the curve)
You can sub this value for y into the equation, and end up with a value for x
It is much faster/easier than calculus.

Edit: how many marks for this question? If it's just one or two, they won't be expecting you to differentiate.
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Rudeboy999
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this is at gcse level btw
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englishman129
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(Original post by assmaster)
For this question, you can get the answer much more easily without calculus (although it would work too, it's just waaay longer)

It helps to imagine the curve, and the lowest point on that curve will be y=7 (due to the translation of the curve)
You can sub this value for y into the equation, and end up with a value for x
It is much faster/easier than calculus.

Edit: how many marks for this question? If it's just one or two, they won't be expecting you to differentiate.
BTW i'm not asking the question...i just responded saying you have to differentiate and i know how to do it. It's the original poster who dosen't lol - everyone keeps quoting me.
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englishman129
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(Original post by Rudeboy999)
this is at gcse level btw
dude, i've never covered it in my normal maths syllabus, do you even have to?
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assmaster
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(Original post by englishman129)
BTW i'm not asking the question...i just responded saying you have to differentiate and i know how to do it. It's the original poster who dosen't lol - everyone keeps quoting me.
I know sweetie, the OP will be watching the thread and will hopefully read what I said... :rolleyes:
Also you don't have "Thread Starter" under your username :yep:
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lolhenry
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This is a GCSE level, although A* stuff . The answer is right there after youcomplete the square.
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M_E_X
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(Original post by assmaster)
I know sweetie, the OP will be watching the thread and will hopefully read what I said... :rolleyes:
Also you don't have "Thread Starter" under your username :yep:
You never call me sweetie, yet this scrot gets it?

*cries*
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englishman129
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Lol
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assmaster
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(Original post by M_E_X)
You never call me sweetie, yet this scrot gets it?

*cries*
Cutie?
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englishman129
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(Original post by M_E_X)
You never call me sweetie, yet this scrot gets it?

*cries*
awwwwww how upsetting , i duno wot i even done to annoy you lol
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