In the expansion of (x2+x31)n the general term is Tr+1=Crn(x2)n−r(x31)r
=Crnx2n−2r−3r=Crnx2n−5r
For coefficient of x, 2n−5r=1
⇒r=52n−1
So, we have the coefficient as C52n−1n
Using, the given value and Crn=Cn−rn
⇒C52n−1n=C23=Cn−23nn
If 52n−1=23⇒n=58 and if 52n−1=n−23⇒n=38
Thus, the minimum value of ′n′ is 38.