For (3x3−2x2+x55)10the general term is given by
Tr+1=r1!r2!r3!10!(3)r1(−2)r2(5)r3(x)3r1+2r2−5r3
For term independent of x the exponent 3r1+2r2−5r3=0…(1)
Also we know r1+r2+r3=10⋯(2)
From (1) and (2), we get
r1+2(10−r3)−5r3=0
i.e. r1+20=7r3
So r1,r2,r3=1,6,3
Hence the constant term =1!6!3!10!(3)1(−2)6(5)3
=29⋅32⋅54⋅71
⇒k=9