By synthetic division,
-5 | 1 -6 -42 79
. | -5 55 -65
- - - - - - - - - - - - - - - - -
. | 1 -11 13 14


When

, you're left with a remainder of 14.
Volume of a cylinder = πr²h
1256 = (3.14) x (r)² x (13)
1256 = 40.82r²
r² = 1256 ÷ 40.82
r² = 30.769
r = √30.69
r = 5.547
Diameter = Radius x 2
Diameter = 5.547 x 2
Diameter = 11.09 units (nearest hundredth)
Answer:
I think you have not written the full question