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help in mathe

Intermediate

Occupation: AUT

Sunday, April 10th 2005, 5:35pm

help in mathe

kann mir mal bitte jemand diese gleichung auflösen:

9(x-3)²+4(2x+1)²=(5x-2)²

ich probier mit meinem neffen schon seit 1 stunde rum. ergebnis sollte 4,5 sein. bitte um den rechenweg

danke

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Sage

Location: Köln

Occupation: GER

Sunday, April 10th 2005, 5:43pm

9(x² - 6x + 9) + 4(4x² + 4x +1) - 25x² + 20x - 4 = 0

9x² - 54x + 81 + 16x² + 16x + 4 - 25x² + 20x - 4 = 0

- 18x + 81 = 0

x = 4,5

Bitte

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Professional

Occupation: GER

Sunday, April 10th 2005, 5:47pm

Binomische Formel auflösen, ausmultiplizieren und x isolieren.

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Professional

Sunday, April 10th 2005, 5:47pm

9*((x-3)*(x-3))+4*((2x+1)*(2x+1))=(5x-2)+(5x-2)

9*(x²-6x+9)+4*(4x²+4x+1)=25x²-20x+4

9x²-54x+81+16x²+16x+4=25x²-20x+4

25x²-38x+85=25x²-20x+4

-38x+81=-20x

18x+81=0

18x=81

x=81/18

x=4,5

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Master

Location: Berlin

Occupation: GER

Sunday, April 10th 2005, 5:48pm

9(x²-6x+9)+4(4x²+4x+1)=25x²-20x+4
(9x²-54x+81)+(16x²+16x+4)=25x²-20x+4
25x²-38x+85=25x²-10x+4 |-25x²|+38x |-4
81=18x |:18
4,5=x
:bounce:

:bounce:

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Sage

Occupation: GER

Sunday, April 10th 2005, 5:48pm

9(x²-6x+9)+4(4x²+4x+1)-(25x²-10x+4)=0
-28x+81=0
28x=81
x=81/18 ->4,5

This post has been edited 1 times, last edit by "ZwerG_Serge" (Apr 10th 2005, 5:48pm)

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Professional

Occupation: GER

Sunday, April 10th 2005, 5:50pm

Aus welcher klassenstufe ist die Aufgabe?

Edit, weil serge auch editiert hat

This post has been edited 1 times, last edit by "LXIII_universe" (Apr 10th 2005, 5:51pm)

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Professional

Location: Nottuln

Occupation: GER

Sunday, April 10th 2005, 5:53pm

jgst 8?

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Intermediate

Occupation: AUT

Sunday, April 10th 2005, 5:55pm

danke, das beispiel ist aus der 3.klasse gym also 7. schulstufe

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Sage

Occupation: GER

Sunday, April 10th 2005, 6:08pm

Quoted

Original von LXIII_universe
Aus welcher klassenstufe ist die Aufgabe?

Edit, weil serge auch editiert hat

kleiner Rechenfehler :p

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Intermediate

Occupation: AUT

Sunday, April 10th 2005, 6:13pm

ich hatte beim ersten binom immer 9x² - 54x - 81 raus. naja, shit happens

danke nochmals an alle

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Master

Occupation: GER

Sunday, April 10th 2005, 6:18pm

minus*minus=plus, deswegen +81

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