9.根据题意f(x)=3sin(2x+g)+3cos(2x)=23sin(2x+)+cos(2x+y)23sin(2x+y+).若f(x)为偶函数,则+=kx+号,即=k+,k∈Z结合选项,可知当k=-1,即=时,f(x=23cos2x,满足在[0]上为增函数10.A依题意,∵当n≥2时,an,S-1,成等比数列,∴(S.-1)2=aSn即(S-1)2=(s-s-)sn2s11s.--1=0s.-1=.--.-1----11成等差数列∵首项为11-1--2s.-1--n-1,即s.n+1n+1∴数列{}的前n项和T=2+3+…+(n+1)=n+3