证明：由已知,取x=0,得 0≤f(x)≤0 =>f(0)=0.由当x->0+时,1=lim x/x≤ limf(x)/x ≤ lim (x^2+x)/x=1=>limf(x)/x=1 (夹逼准则)由当x->0-时,1=lim (x^2+x)/x ≤ limf(x)/x ≤ lim x/x=1=>limf(x)/x=1 (夹逼准则)所以...
