急!高一数学问题!在线等!x^2,/x/≥1,1 设f（x）={x,/x/＜1, g(x)是二次函数,若f[g(x)]的

急!高一数学问题!在线等!
x^2,/x/≥1,
1 设f（x）={x,/x/＜1, g(x)是二次函数,若f[g(x)]的值域是[0,+∞), 则g(x)的值域是?
2 若对一切实数a,b均有f(a×b)=f(a)×f(b),且f(0)≠0,则f(2009)=?
3 在直角坐标系内,一运动质点经过点A(0,9),其轨迹方程为y=ax^2+c(a＜0).区间D:(6,7)为x轴上给定的区间.⑴为使质点落在D内,求a的取值范围;⑵若质点运动时经过点P(2,8.1),问其能否落在区间D内,并说明理由.
f(x),f(x)≤g(x)
4 若f(x)=3-2/x/,g(x)=x^2-2x,定义f(x)△g(x)={g(x),f(x)＞g(x).求F(x)=f(x)△g(x)的最大值.
(请给出详细解答,谢谢啦^^^^^^^^^^^^)
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