Step OneSubtract cube root 1/9 to the left hand side. Or subtract cube root (1/9) from both sides.
Step Two.
There is a minus sign in front of
![{-}\sqrt[3]{ \frac{1}{9} }](https://tex.z-dn.net/?f=%20%7B-%7D%5Csqrt%5B3%5D%7B%20%5Cfrac%7B1%7D%7B9%7D%20%7D%20)
We must get rid of it. Because it is a minus in front of a cube root, we can bring it inside the cube root sign like so, and make it a plus out side the cube root sign
Step ThreeWrite the Left side with the minus sign placed in the proper place
Step FourEquate cube root b with cube root (-1/9)
Step FiveEquate the cube root of a with what's left over on the left
Step 6.
I'll just work with b for a moment.
Cube both sides of cube root (b) = cube root (-1/9)
![\sqrt[3]{b} ^{3} =\sqrt[3]{ \frac{-1}{9} }^3}](https://tex.z-dn.net/?f=%20%5Csqrt%5B3%5D%7Bb%7D%20%5E%7B3%7D%20%3D%5Csqrt%5B3%5D%7B%20%5Cfrac%7B-1%7D%7B9%7D%20%7D%5E3%7D%20)

Step seventhe other part is done exactly the same way
a = cuberoot(2) - 1.
What you do from here is up to you. It is not pleasant.
Is this clearer?
a + 2b should come to cuberoot(2) - 1 - 2/9
a + 2b should come to cuberoot(2) - 11/9
I hope a person is marking this. I wonder how many of your class mates got it.