- #1

Monique

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^{2}=9, what is the value of y?

And the answer is not -1.. what is the trick here that I'm missing? The answer is supposed to be 5.

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- Thread starter Monique
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- #1

Monique

Staff Emeritus

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And the answer is not -1.. what is the trick here that I'm missing? The answer is supposed to be 5.

- #2

NateTG

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Monique said:^{2}=9, what is the value of y?

And the answer is not -1.. what is the trick here that I'm missing? The answer is supposed to be 5.

[tex]x+2y=2[/tex]

so

[tex]x=2-2y[/tex]

so

[tex](x+y)^2=(2-2y+y)^2=(2-y)^2=9[/tex]

square root of both sides:

[tex]\pm (2-y)=3[/tex]

[tex]-3=2-y[/tex] or [tex]3=2-y[/tex]

So the solutions (note the plural) are:

[tex](-8,5)[/tex] and [tex](4,-1)[/tex]

I'm guessing you forgot that every number has two square roots. ;)

- #3

Monique

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I should be doing other things at 2 in the morning :grumpy:

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monique is a cutie :blush:

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