radical y squared + 2 = y-1

i believe you have to square both sides, but i'm not sure. please help

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- Jan 11th 2007, 03:28 PMbobbyfisherradicals
radical y squared + 2 = y-1

i believe you have to square both sides, but i'm not sure. please help - Jan 11th 2007, 06:26 PMtopsquark
I'm not quite sure of what the equation is. It just doesn't make sense to me. What you have written is either

or

Neither of which should pose a problem.

I'm going to assume that you wrote it wrong and meant:

<-- Square both sides

which you can solve using the quadratic formula:

The bad news is that whenever you square both sides of an equation you should always check to make sure you haven't added a new solution and these forms are messy to substitute back into the original equations. I'll give you peace of mind by telling you that only the "+" solution is correct.

-Dan - Jan 11th 2007, 10:03 PMCaptainBlack
If:

,

then:

which simplifies to:

or .

Now the squaring can introduce spurious solutions so this needs to be

substituted back into the original equation to check that it is a solution.

Doing this we find it is not a solution so the equation has no solutions!

RonL