JM Curdy
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Registered: 20th Jan 05
Location: Stranraer, Scotland
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(a)
Show that the function f(x) = 2xsquared + 8x - 3 can be written in the form f(x) = a(x + b)squared + c where a,b and c are constants
(b)
hence, or otherwise find the coordinates of the function f
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John
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Registered: 30th Jun 03
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Is this some American's school homework?
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Generation
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Registered: 7th Jul 09
Location: Essex
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Why
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JM Curdy
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Registered: 20th Jan 05
Location: Stranraer, Scotland
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to impress a wee lassie, probably get my hole. been a long time since ive worked something like that out, dont want to miss out on a golden opertunity
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Generation
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Registered: 7th Jul 09
Location: Essex
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If she's impressed by stuff like that, don't let her see your spelling
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baza31
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Registered: 19th Apr 03
Location: yorkshire
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quote:
Originally posted by Generation
If she's impressed by stuff like that, don't let her see your spelling
Fpmsl
I wouldn't have a clue so I'll take a guess and say 15 
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Ste
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Registered: 5th Mar 03
Location: Taif, Saudi Arabia
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Ok, here's your answers, but pics must be provided or I'll find her and tell her I solved it for you.
a) f(x) = 2(x^2 + 4x) -3
b) Continuing with completing the square:
f(x) = 2(x^2 + 4x) -3
f(x) = 2(x^2 + 4x + (4 - 4)) -3 Here I am essentially adding 0, by adding (4-4) but by doing this I can factorise it.
f(x) = 2(x^2 + 4x + 4 - 4) -3
f(x) = 2(x+2)^2 - 4) -3
Now expand:
f(x) = 2(x+2)^2 - 4) -3
f(x) = 2(x+2)^2 -8 -3
f(x) = 2(x+2)^2 - 11
Hence this is the form we want:
f(x)=a(x+b)^2+c
Therefore a =2, b=2, c=-11
Hope this was informative and easy to follow mate :-)
Have a nice day!
Whoops forgot about the extension. Don't worry it's very easy. This form "f(x)=a(x-b)^2+c" is called vertex form. * Note the "-b". When you have this form you can read off the turning point.
In this form, b is the x coordinate and c is the y coordinate.
In your case f(x) = 2(x+2)^2 - 11, b = -2, and c = -11
Thus the turning point is (-2,-11)
Note that b is -2 because using the form f(x)=a(x-b)^2+c, b is the x coordinate. but the b has a "-" sign infront of it. In your question as it is + 2, the x coordinate is -2 because two negatives make a positive. If you don't understand maybe this will help.
f(x) = 2(x+2)^2 - 11
That equation is the same as this:
f(x) = 2(x-(-2))^2 - 11 --> this one is in vertex form, therefore you can see that b is = -2
This is year 12 maths btw
I would rather lose by a mile because i built my own car, than win by an inch because someone else built it for me.
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Hammer
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Registered: 11th Feb 04
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Well done that man, you have just allowed the OP to fuck a 14 year old.
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SVM 286
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Registered: 13th Feb 05
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Sweet Jesus I feel thick.
This is worse than trying to watch Only Connect.
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JonnyJ
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Registered: 23rd Sep 05
Location: Scotchland
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Its ok Jim, I haven't got the foggiest what all that jive means either.
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Nath
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Registered: 3rd Apr 02
Location: MK
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This just proves that maths is useless. Year 12? I'm now 29 and never needed to use the above EVER.
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Dave
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Registered: 26th Feb 01
Location: Lancs
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Year 12 is A level though isn't it?
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Nath
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Registered: 3rd Apr 02
Location: MK
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AS level, basically first year of A levels.
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Gavin
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Registered: 3rd Apr 02
Location: West Midlands
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quote:
Originally posted by Nath
This just proves that maths is useless. Year 12? I'm now 29 and never needed to use the above EVER.
pew pew pew pewwwww
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Ian
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Registered: 28th Aug 99
Location: Liverpool
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I use it all the time.
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SVM 286
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Registered: 13th Feb 05
Location: pain
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quote:
Originally posted by JonnyJ
Its ok Jim, I haven't got the foggiest what all that jive means either.
 Cheers Jonny
:utterrelief:
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SVM 286
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Registered: 13th Feb 05
Location: pain
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quote:
Originally posted by Ian
I use it all the time.
Do you really Ian, or was that typed with a poker face? 
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corsa120
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Registered: 4th May 02
Location: Northamptonshire
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im a qualified engineer to hnc level and i had to do this shit for 4 years of my apprenticeship..... im now 30 years old and have used probably less than 10% of the stuff ive done for my job in real life, i use more triganometry than anything else.......... also reckon ive forgot how to do most things anyways would have to refer to old college work for some help lol, most help college gave me was simple maths like working out rpm speeds and sharpening a drill, these have proved much more useful.
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Russ
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Registered: 14th Mar 04
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As if you're gonna get da puss puss from doing her homework.
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Hammer
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Registered: 11th Feb 04
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quote:
Originally posted by corsa120
im a qualified engineer to hnc level
You've done an HNC in Engineering then?
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corsa120
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Registered: 4th May 02
Location: Northamptonshire
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Sorry hammer if you want to be politically correct and pedantic ive done a recognised engineering apprenticeship... ever so sorry i castrate myself before you and beg for your forgiveness?
[Edited on 30-12-2012 by corsa120]
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SVM 286
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Registered: 13th Feb 05
Location: pain
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Prostrate 
(unless you were joking)
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corsa120
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Registered: 4th May 02
Location: Northamptonshire
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SVM 286
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Registered: 13th Feb 05
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Ste
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Registered: 5th Mar 03
Location: Taif, Saudi Arabia
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So did you tap it?
I would rather lose by a mile because i built my own car, than win by an inch because someone else built it for me.
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