binomial theorem qn (1 Viewer)

[Masaken]

I've found the coefficients, did fourth coefficient - third coefficient = third coefficient - second coefficient, but it ended up looking clunky (had to use the quadratic formula and it got all confusing). How would you go about solving this?

 

[Masaken]

working out so far:

is there anything i didn't do/anything i did wrong?

 

[Drongoski]