Sunday, July 28, 2013

solve square root equation x=6[squareroot(x-2)-1]?

We'll impose the constraint of existence of the square
root:


x-2>=0


We'll add
2 both sides:


x>=2


The
interval of admissible values is [2 ; +infinite).


We'll
re-write the given equation. We'll isolate 6sqrt(x-2) to the right side. For this
reason, we'll add 6 both sides:


6+x =
6sqrt(x-2)


We'll square raise both sides. For squaring the
binomial from the left side, we'll use the formula;


(a+b)^2
= a^2 + 2ab + b^2


36 + 12x + x^2 =
36(x-2)


 We'll remove the
brackets:


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


We'll subtract
36x-72:


x^2 - 24x + 108 =
0


We'll apply the quadratic
formula:


x1=[24+ sqrt
(24^2-4*108)]/2


x1 =
(24+12)/2


x1 =
36/2


x1=18


x2=(24-12)/2


x2=6


Since
both values belong to the interval [2 ; +infinite), we'll validate them as solutions of
the given equation: x1 = 18 and x2 = 6.

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