Help! How to make an extraneous equation? I need to make an equation that when substituted into it's original equation, doesn't equal the original answer (I hope that makes sense) and the equation I made is non extraneous. My equation was the square root of (x+9) plus 2 = 20. But, it was non extraneous.

Question

anonymous · Answer

try $$\sqrt{x+9}+2=1$$

anonymous · Answer

That worked, thanks!
to be sure, is the solution x=-7?

anonymous · Answer

and when I tried to see if it was extraneous, I got 4=-1

anonymous · Answer

there is no solution, but i guess the "extraneous" one would be $-8$

anonymous · Answer

Sorry, I'm confused. I solved the equation and got -7 haha

anonymous · Answer

$$\sqrt{x+9}+2=1\
\sqrt{x+9}=-1\
x+9=1\
x=-8$$

anonymous · Answer

oh ok! I put -7 instead of 8 for some reason. Thanks!

anonymous · Answer

yw