2
x2
-
x
p
The general term of) 6 expansion is Tr+ 1=
C
r
six
(
2
x2
)6-r(-
x
p
)r=(-
1
p
)r26-r
C
r
six
x3r- 12
Let 3r- 12=0 to get r=4.
Therefore, an item without an X is (-
1
p
)422
C
four
six
∴(-
1
p
)422
C
four
six
=
20
27
The solution is p=3.
So the answer is 3.