# How to solve #x^(2/3) - 6x^(1/3) + 5 = 0#? (substituting using u)

##### 1 Answer

Oct 26, 2017

I got

#### Explanation:

We have

#(x^(1/3))^2 - 6x^(1/3) + 5 = 0#

Then letting

#u^2 - 6u + 5 = 0#

#(u - 5)(u - 1) = 0#

#u = 5 or 1#

Now we reverse the substitution.

#x^(1/3) = 5 or x^(1/3) = 1#

#(x^(1/3))^3 = 5^3 or (x^(1/3))^3 = 1^3#

#x = 125 or 1#

Hopefully this helps!