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savvers
 3 years ago
4sqrt(x+9)=20 can anyone help?
savvers
 3 years ago
4sqrt(x+9)=20 can anyone help?

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geoffb
 3 years ago
Best ResponseYou've already chosen the best response.2\[4 \sqrt{(x+9)} = 20\] Like this? At what part are you getting stuck?

savvers
 3 years ago
Best ResponseYou've already chosen the best response.0well i get x=16 but when i try to see if its true i get 20=20

geoffb
 3 years ago
Best ResponseYou've already chosen the best response.2Yeah, with that 4 outside the square root, I think it's undefined.

savvers
 3 years ago
Best ResponseYou've already chosen the best response.0yeah your probably right. extraneous solution?

geoffb
 3 years ago
Best ResponseYou've already chosen the best response.2If we defined \(y\) as \(\sqrt{(x+9)}\), we would get \(4y = 20\), with \(y = 5\), and there is no way \(\sqrt{(x+9)} = 5\)

savvers
 3 years ago
Best ResponseYou've already chosen the best response.0hmmm i dont know. but when we divide 4 we get \[\sqrt{x+9}=5\]

geoffb
 3 years ago
Best ResponseYou've already chosen the best response.2\(\large{\sqrt{x} = i \sqrt{x}}\) right?

geoffb
 3 years ago
Best ResponseYou've already chosen the best response.2Okay, can we use that somehow?

geoffb
 3 years ago
Best ResponseYou've already chosen the best response.2Oh wait... We can square both sides, right?

savvers
 3 years ago
Best ResponseYou've already chosen the best response.0and we get x+9=25 because 5x5=25

geoffb
 3 years ago
Best ResponseYou've already chosen the best response.2Right, so you were right with 16; it is an extraneous root.

savvers
 3 years ago
Best ResponseYou've already chosen the best response.0yeah it looks like that then and thanks man
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