SOLUTION: Find the real solutions of each equation. rt{10 + rt{x}} = rt{x}

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Question 1207630: Find the real solutions of each equation.

rt{10 + rt{x}} = rt{x}

Answer by Edwin McCravy(20055) About Me  (Show Source):
You can put this solution on YOUR website!

sqrt%2810+%2B+sqrt%28x%29%29+=+sqrt%28x%29

Square both sides:

10+%2B+sqrt%28x%29+=+x

Isolate the root:

sqrt%28x%29+=+x-10

Square both sides:

x=x%5E2-20x%2B100

x%5E2-21x%2B100

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+

x+=+%28-%28-21%29+%2B-+sqrt%28+%28-21%29%5E2-4%2A1%2A100+%29%29%2F%282%2A1%29+

x+=+%2821+%2B-+sqrt%28441-400+%29%29%2F2+

x+=+%2821+%2B-+sqrt%2841%29%29%2F2+

But when you square both sides of an equation, you have to check your answers,
for some, or even ALL, of your answers may be extraneous.

So we check.  It would be very time consuming to check the answers in exact
form, so get their decimal approximations. 

x+=+%2821+%2B+sqrt%2841%29%29%2F2+ is approximately 13.70156212

sqrt%2810+%2B+sqrt%28x%29%29+=+sqrt%28x%29

sqrt%2810+%2B+sqrt%2813.70156212%29%29+=+sqrt%2813.70156212%29

sqrt%2810+%2B+3.701562119%29+=+3.701562119

sqrt%2813.701562119%29+=+3.701562119

3.701562119%29+=+3.701562119

That checks, so we know that is a solution.

Now let's check the other solution

x+=+%2821+-+sqrt%2841%29%29%2F2+ is approximately 3.701562119

sqrt%2810+%2B+sqrt%28x%29%29+=+sqrt%28x%29

sqrt%2810+%2B+sqrt%283.701562119%29%29+=+sqrt%283.701562119%29

sqrt%2810+%2B+1.923944417%29+=+1.923944417

sqrt%2811.923944417%29+=+1.923944417

3.453106488+=+1.923944417

As we see, this does not check, so there is only 1 solution,

x+=+%2821+%2B+sqrt%2841%29%29%2F2+

Edwin