To solve the equation and to eliminate the square
roots, we'll square raise both sides:
[sqrt(x^3 - x) +
sqrt(2x - 1)]^2= [sqrt(x^3 + x - 1)]^2
x^3 - x + 2x - 1 +
2sqrt[(x^3 - x)(2x - 1)] = x^3 + x - 1
We'll combine and
eliminate like terms and we'll get:
2sqrt[(x^3 - x)(2x -
1)] = 0
We'll divide by
2:
[(x^3 - x)(2x - 1)] =
0
We'll set each factor as
zero:
x^3 - x = 0
We'll
factorize:
x(x^2-1) = 0
We'll
expand the difference of squares:
x(x-1)(x+1) =
0
We'll set each factor as
zero:
x1 = 0
x-1 =
0
x2 = 1
x+1 =
0
x3 = -1
2x - 1 =
0
2x = 1
x4 =
1/2
Now, we'll check the found results in
equation:
For x1 = 0
sqrt(x^3
- x) + sqrt(2x - 1)= sqrt(x^3 + x - 1)
sqrt(0) + sqrt( -
1)= sqrt( - 1)
But sqrt -1 is
impossible!
For x2 = 1
sqrt(1
-1) + sqrt(2 - 1)= sqrt(1 + 1- 1)
0 + 1 =
1
1=1
So x = 1
is admissible.
For x3 =
-1
sqrt(x^3 - x) + sqrt(2x - 1)= sqrt(x^3 + x -
1)
sqrt(-1 + 1) + sqrt(-2 - 1)= sqrt(-1 -1-
1)
sqrt -3 = sqrt-3
But,
sqrt-3 is impossible!
For x =
1/2
sqrt(x^3 - x) + sqrt(2x - 1)= sqrt(x^3 + x -
1)
sqrt(1/8- 1/2) + sqrt(2/2 - 1)= sqrt(1/8 +1/2 -
1)
But sqrt -3/8 is
impossible!
So, the only admissible solution
of the equation is x = 1.
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