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Mathematics 7 Online
OpenStudy (jacksonjrb):

Need help with radical equation. Will give medals!

OpenStudy (puzzler7):

What do you need this time?

OpenStudy (jacksonjrb):

\[\sqrt{x-3}+\sqrt{x}=3\]

OpenStudy (jacksonjrb):

The answer is 4. I just don't know how to get there algebraically...

OpenStudy (puzzler7):

Square both sides to get\[x-3+2\sqrt{x^2-3x}+x=9\]then rearrange to get\[\frac{12-2x}{2}=\sqrt{x^2-3x}\]\[(6-x)^2=x^2-3x\]

OpenStudy (puzzler7):

Is that good?

OpenStudy (jacksonjrb):

Then what?

OpenStudy (jacksonjrb):

And (6-x)^2 doesn't equal 12-2x

OpenStudy (puzzler7):

Sorry, I simplified to 6-x, then squared both sides, in the same step.

OpenStudy (puzzler7):

\[36-12x+x^2=x^2-3x\]\[36-12x=-3x\]

OpenStudy (jacksonjrb):

Ah

OpenStudy (jacksonjrb):

Thanks!

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