Lösung 4.1:7d

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We rewrite the equation in standard by completing the square for the x- and y-terms:
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We rewrite the equation in standard form by completing the square for the ''x''- and ''y''-terms,
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<math>x^{2}-2x=\left( x-1 \right)^{2}-1^{2}</math>
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<math>y^{2}+2y=\left( y+1 \right)^{2}-1^{2}</math>
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{{Displayed math||<math>\begin{align}
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x^{2} - 2x &= (x-1)^2 - 1^2\,,\\[5pt]
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y^{2} + 2y &= (y+1)^2 - 1^2\,\textrm{.}
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\end{align}</math>}}
Now, the equation is
Now, the equation is
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{{Displayed math||<math>\begin{align}
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(x-1)^2 - 1 + (y+1)^2 - 1 &= -2\\
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\Leftrightarrow\quad (x-1)^2 + (y+1)^2 &= 0\,\textrm{.}
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\end{align}</math>}}
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<math>\begin{align}
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The only point which satisfies this equation is <math>(x,y) = (1,-1)</math> because, for all other values of ''x'' and ''y'', the left-hand side is strictly positive and therefore not zero.
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& \left( x-1 \right)^{2}-1+\left( y+1 \right)^{2}-1=-2 \\
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& \Leftrightarrow \quad \left( x-1 \right)^{2}+\left( y+1 \right)^{2}=0 \\
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\end{align}</math>
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The only point which satisfies this equation is
 
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<math>\left( x \right.,\left. y \right)=\left( 1 \right.,\left. -1 \right)</math>
 
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because, for all other values of
 
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<math>x</math>
 
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and
 
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<math>y</math> , the left-hand side is strictly positive and therefore not zero.
 
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{{NAVCONTENT_START}}
 
<center> [[Image:4_1_7_d.gif]] </center>
<center> [[Image:4_1_7_d.gif]] </center>
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{{NAVCONTENT_STOP}}
 

Version vom 11:42, 8. Okt. 2008

We rewrite the equation in standard form by completing the square for the x- and y-terms,

Vorlage:Displayed math

Now, the equation is

Vorlage:Displayed math

The only point which satisfies this equation is \displaystyle (x,y) = (1,-1) because, for all other values of x and y, the left-hand side is strictly positive and therefore not zero.


Image:4_1_7_d.gif