SOLUTION: Remove radical and simplify.. radical of x-3 plus radical of 2x equals three?

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Question 206892: Remove radical and simplify..
radical of x-3 plus radical of 2x equals three?

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
Remove radical and simplify..
radical of x-3 plus radical of 2x equals three?

sqrt%28x-3%29%2Bsqrt%282x%29=3

Isolate the more complicaed radical term.  So we
isolate sqrt%28x-3%29

sqrt%28x-3%29=3-sqrt%282x%29

Square both sides:

%28sqrt%28x-3%29%29%5E2=%283-sqrt%282x%29%29%5E2

Write the square on the right as the product
of the binomial with itself:

x-3=%283-sqrt%282x%29%29%283-sqrt%282x%29%29+

Use FOIL on the right sides:

x-3=9-3sqrt%282x%29-3sqrt%282x%29%2B%28sqrt%282x%29%29%5E2+

x-3=9-6sqrt%282x%29%2B+2x

Isolate the radical term:

6sqrt%282x%29=12%2Bx

Square both sides:

6sqrt%282x%29%29%5E2=%2812%2Bx%29%5E2

6%5E2%2A%28sqrt%282x%29%29%5E2=%2812%2Bx%29%2812%2Bx%29

36%282x%29=144%2B12x%2B12x%2Bx%5E2

72x=144%2B24x%2Bx%5E2

Get 0 on the left:

0=x%5E2-48x%2B144

That doesn't factor, so we have
to use the quadratic formula:

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

a=1, b=-48,  c=144

  

 x+=+%2848+%2B-+sqrt%28+2304-576+%29%29%2F2+ 

 x+=+%2848+%2B-+sqrt%281728%29%29%2F2+

 x+=+%2848+%2B-+sqrt%28576%2A3%29%29%2F2+

 x+=+%2848+%2B-+sqrt%28576%29sqrt%283%29%29%2F2+

 x+=+%2848+%2B-+24sqrt%283%29%29%2F2+

Make two fractions:

x+=+48%2F2+%2B-+24sqrt%283%29%2F2+

x+=+24+%2B-+12sqrt%283%29+

Those have decimal values

x=24%2B12sqrt%283%29=44.78460969

x=24-12sqrt%283%29=3.215390309

Check these in the original with a
calculator.  The first one doesn't
check but the second one does.

So the only solution is

x=24-12sqrt%283%29=3.215390309


Edwin