The Quadratic Equation

Right no matter how many I try to solve this, it never comes with the correct answer!

Solve the quadratic equation
(2x + 3)^2= 15
(I won't go through the workings of my failed attempts)

So far I have had x=1.732... or x=1.732... AND x=0.589 or x=-5.089 by trying different ways. No matter what I have tried I just cannot solve this little bugger, could somebody give me a hand please?



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VT Driver
Broders

hmm

u get

4xsqaured +12x +9 = 15

thus

2xsquared + 6x - 3 = 0

and then work it from there (into the equation)

wots the right answer meant to be?



Edited 3 time(s). Last edit at 06/13/2005 10:57PM by ChrisB.

well, i got 2. not gd at maths tho soz


cummon, u gotta be expecting that lame ass joke

2.25?



RedSam
Winner: Not the Nickv Comment of the Year 2009
Due to the voting system in Germany, Governments are always made up of coalitions of different parties. At the last election, an almost unprecidented result saw the CDU/CSU (rough equivilant of the Conservatives) go into Government with the SPD (rough equivilant of Labour)

x = (-b +/- (sq(b^2-4ac)) / 2a) is the quadratic equation.

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Edited 1 time(s). Last edit at 06/13/2005 10:40PM by 97kirkc.

yes, well the answer is supposed to be:
x=0.44 or x=-3.44

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VT Driver
Broders

*head explodes*

I HATE maths1!!

answer is: x= 0.4365 or -3.4365 (4dp) or 0.44, - 3.44 (2dp)

(2x + 3)^ 2 =15

4x^2 + 12x - 6 = 0

A=4 B=12 C=-6

x = (-b +/- (sq(b^2-4ac)) / 2a)

therefore:

-12 +/- (sq(144 - 4x4x-6)) / 8)

-12 +/- (sq(240)) / 8)

x = -12 + 15.492 / 8 OR x = -12 - 15.492 / 8

x = 0.4365 (0.44) OR x= -3.4365 (-3.44)



Hope you understand, cause they come alot more complicated :P

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or even cheat

square root of 15 = +/- 3.8729 [5sf]

therefore 3.8729 = 2x +3

0.8729 = 2x

x = 0.44 (2sf)


AND: - 3.8729 = 2x + 3

-6.8729 = 2x

x = - 3.44 (2sf)



Edited 1 time(s). Last edit at 06/13/2005 10:56PM by ChrisB.

4xsqaured +6x +9 = 15

no

4x^2 +12x+ 9 = 15

=> 4x^2+12x-6 = 0

=> 2x^2+6x-3= 0


therefore,

x = (-6+-sqrt(6^2-4*2*-3))/2*2

=> (-6+-sqrt(60))4

x=0.44 or x=-3.44

EASY :D

yup Chris, I did it that way too, but as he said quadratic i did it the way hes probably meant to do it :P

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Edited 1 time(s). Last edit at 06/13/2005 10:59PM by 97kirkc.

beardless where did u get that from "4xsqaured +6x +9 = 15 "

meah good to see you around!

hehe broders are you revising for maths?
not till wednesday :P for me.
GCSE's have bene suprisingly easy :|

Wait till you start differential equations and integration of parametric equations

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I have a A2 level maths exam on thursday and im shitting bricks!! Pure 2 for any one who knows what the math course consists of???

You sure your exam is on Thursday ? My P2 is on Monday...

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p2 is piss easy, p6 is when it starts getting hard...

NickKK Wrote:
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> Wait till you start differential equations and
> integration of parametric equations
>
>


That's easy, wait until you move 2 levels of Calculus farther, and have a horrible Chinese teacher who barely speaks English (when English is not your first language as well). Now that is hard, and the reason I quit my Economics major

Button14 Wrote:
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> I have a A2 level maths exam on thursday and im
> shitting bricks!! Pure 2 for any one who knows
> what the math course consists of???
>
>


w00t, I failed that one, twice :D

after getting an A at GCSE, just to show how easy they are

Same in Scotland.

1 (equivelent to an A) in Standard grade (GSCE level), and failed the next level up. The gap between them is huge. GCSEs/Standard Grades are FAR too easy

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