- #1

aquitaine

- 21

- 9

the equation is:

y = cuberoot(x+sqrt(1+x^2)) + cuberoot(x-sqrt(1+x^2))

I tried replacing X with Y, and solving for Y

and getting rid of the cube roots by cubing both sides

X^3 = y + sqrt(1+y^2) + y - sqrt(1+y^2)

simplifying a bit (the square roots go away)

x^3 = 2y

so

y = (1/2)x^3

Yet the book I'm using says the answer is y=(1/2)(3x+x^3)

What did I do wrong?