a(n+1)=0.6an+0.2
a(n+1)-0.5=0.6an-0.3=0.6(an-0.5)
故{an-0.5}是等比数列,首项a1-0.5,公比是0.6
即an-0.5=(a1-0.5)*0.6^(n-1)
an=(a1-0.5)*0.6^(n-1)+0.5
题目中应该有a1=...吧,代入就行了.