1.证：a(n+1)=an²+4an+2a(n+1)+2=an²+4an+4=(an+2)²log3[a(n+1)+2]=log3[(an+2)²]=2log3(an+2)log3[a(n+1)+2]/log3(an+2)=2,为定值.log3(a1+2)=log3(1+2)=log3(3)=1数列{log3(an+2)}是以1为首项...第三问呢第三问你还没写。