2.一质点做直线运动,其位移sss与时间ttt的关系为s=t2+2ts=t^{2}+2ts=t2+2t,设其在t∈[2t\in [2t∈[2,3]3]3]内的平均速度为v1v_{1}v1,在t=2t=2t=2时的瞬时速度为v2v_{2}v2,则v1v2=(\frac{v_1}{v_2}=(v2v1=( )))