6.若函数f(x)=x2+mx+nf(x)=x^{2}+mx+nf(x)=x2+mx+n在区间(−1,1)(-1,1)(−1,1)上有两个零点,则n2−m2+2n+1n^{2}-m^{2}+2n+1n2−m2+2n+1的取值范围是((( )))