Thursday, October 10, 2013

Solve for real x the equation x=6[(x-2)^1/2-1].

For the beggining, we'll impose constraint of existence of
the square root:


x - 2 >=
0


x >= 2


The real
solutions of the equation have to belong to the range [2 ;
+infinite).


Now, we'll solve the equation. We'll start by
removing the brackets:


x = 6sqrt(x-2) -
6


We'll add 6 both sides, in order to isolate the square
root to the right side.


x + 6 =
6sqrt(x-2)


Now, we'll square raise to eliminate the square
root;


x^2 + 12x + 36 = 36x -
72


We'll subtract 36x -
72:


x^2 + 12x + 36 - 36x + 72 =
0


We'll combine like
terms:


x^2 - 24x + 108 =
0


We'll apply quadratic
formula:


x1 =[24 + sqrt(576 -
432)]/2


x1 = (24 + 12)/2


x1 =
18


x2 = (24 - 12)/2


x2 =
6


Since both values belong to the interval of
admissible values, we'll accept them. The solutions of the equation are: {6 ;
18}.

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