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April 30th, 2015, 11:00 AM   #1
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Where did this exponent come from?

Not sure about this, please assist.
The_Ys_Guy is offline  
April 30th, 2015, 11:37 AM   #2
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you were given ...


$y = x-1$

substitute $(x-1)$ for $y$ in the first equation ...

$(x-1)^2 = 5-x^2$
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April 30th, 2015, 11:39 AM   #3
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You are given the two equations $\displaystyle x^2+ y^2= 5$ and $\displaystyle x- y= 1$.

Subtrating $\displaystyle x^2$ from both sides of the first equation, $\displaystyle y^2= 5- x^2$

Adding y to both sides of the second equation, $\displaystyle x= 1+ y$. Subtracting 1 from both sides of that equation, $\displaystyle x- 1= y$

So we can replace y by x- 1 in $\displaystyle y^2= 5- x^2$: $\displaystyle (x- 1)^2= 5- x^2$.

Essentially then the exponent, 2, in that equation come form the exponent on y in the equation $\displaystyle x^2+ y^2= 5$.
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May 1st, 2015, 08:21 PM   #4
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If you are that confused, just write y = y between the second and the third line, hope you understand.
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