SOLUTION: {{{sqrt(2x-3)+x=3}}}

Algebra.Com
Question 146049:
Answer by Edwin McCravy(20054)   (Show Source): You can put this solution on YOUR website!

 

Isolate the radical by adding  to both sides:

 

 

Now square both sides:

 

On the left side, to square a square root takes 
away the radical and the exponent. We write the
right side as 

 

Use FOIL on the right side





See if you can go from there to:



Then we factor the left side:



Use the zero factor principle,
and set each factor = 0:

 gives 

 gives 

But we must check both solutions in the
original equations, because in radical 
equations, there may be extraneous (bogus) 
solutions.

Checking  in the original equation:

 
 
 
 
 
 

That is false, so  is not a solution
to the original equation.

Checking  in the original equation:

 
 
 
 
 
 

That is true, so  is the only solution
to the original equation.

---------------------

If you look at the graph of the left side of 



that is, plot 

you get this curve:



and if you plot the right side of




that is, plot 

on the same graph you see that the only

solution is the x-coordinate of the point

where they intersect. 




They intersect only at (2,3). The x-coordinate
of that point is 2, so  is the only
solution to the system.  But we wonder why we
got the extraneous solution.

We now notice that the curve of the left
side is really part of a slanted parabola,
and if we were to draw in the rest of the 
parabola, that is, the part in light blue 
below: 



we can see that the other part of that parabola
does indeed intersect the graph of the right side,
(the green line) at the point (6,3).  But we 
discard  because the curve of the left side
of the original equation does not include the light
blue part of the parabola.

Edwin

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