Answer:
Step-by-step explanation:
The 9th term is the next-to-last term, where the left term of the binomial is raised to the first power, the right term of the binomial is raised to the 8th power (9-1=8), and the multiplier is 9C8 = 9!/(8!·1!) = 9. This product is ...
9·(3x)^1·(-2y)^8 = 6912xy^8
x = 28
(3x + 6^o) = 90^o
3x = 84^o
