Let me try this again
+ and - radicals

3 sqrt 2y^3 - 5y sqrt 2y + 12 sqrt 8y^3
=3*2y sqrt y - 5y*2y + 12 * sqrt 2*2*2*y*y*y
= 6y sqrt y - 10y + 12*2y sqrt 2y
= 4y sqrt y + 24 sqrt 2 y