Monday, February 10, 2014

Solve the equation (x-4)^1/2=1/(x-4)

First, we'll impose the constraints of existence of the
square root:


x - 4>
=0


x>=4


Now, we'll
solve the equation by raising to square both sides:


(x - 4)
= 1/(x - 4)^2


Now, we'll subtract 1/(x - 4)^2 both
sides:


(x - 4) - 1/(x - 4)^2 =
0


We'll multiply by (x-4)^2 the
equation:


(x - 4)^3 -
1>=0


We'll solve the difference of cubes using the
formula:


a^3 - b^3 = (a-b)(a^2 + ab +
b^2)


(x - 4)^3 - 1 = (x - 4  -1)[(x-4)^2 + x - 4 +
1]


We'll combine like terms inside
brackets:


(x - 5)[(x-4)^2 + x - 4 + 1] =
0


We'll put each factor as
zero:


x - 5 = 0


We'll add 5
both sides:


x =
5


(x-4)^2 + x - 4 + 1 =
0


We'll expand the square:


x^2
- 8x + 16 + x - 3 = 0


We'll combine like
terms:


x^2 - 7x + 13 = 0


We'll
apply quadratic formula:


x1 = [7 + sqrt(49 -
52)]/2


x1 = (7 +
i*sqrt3)/2


x2 = (7 -
i*sqrt3)/2


The roots of the
given equation
are complex numbers. Since there is not any constraint
imposed with regard to the nature of roots, we'll accept them.

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