Given,
Binomial expression (2x3+x3)10, so its nth term is given by,
Tr+1=Cr10(2x3)10−r(x3)r
=Cr10210−r3rx30−4r
Now putting r=0,1,2,.....7 and adding all term we get
(2x3+x3)10=C01021030x30+C1102931x26..............C7102337x2+C8102238x21....
(2x3+x3)10−C8102238x21.......=C01021030x30+C1102931x26..............C7102337x2
Put x=1 both side we get,
510−39(60+20+3)=C01021030+C1102931..............C7102337
510−39(83)=sum of even coefficients
So β=83