Answer:
6 y^5 - 8 y^4 - 10 y^3 + 36 y^2 - 28 y
Explanation:
Expand the following: 
(3 y^3 + 2 y^2 - 7 y) (2 y^2 - 4 y + 4) 
 
 | | | | 3 y^3 | + | 2 y^2 | - | 7 y | + | 0 
 | | | | | | 2 y^2 | - | 4 y | + | 4 
 | | | | 12 y^3 | + | 8 y^2 | - | 28 y | + | 0 
 | | -12 y^4 | - | 8 y^3 | + | 28 y^2 | + | 0 | + | 0 
6 y^5 | + | 4 y^4 | - | 14 y^3 | + | 0 | + | 0 | + | 0 
6 y^5 | - | 8 y^4 | - | 10 y^3 | + | 36 y^2 | - | 28 y | + | 0: 
Answer: 6 y^5 - 8 y^4 - 10 y^3 + 36 y^2 - 28 y