a^2+1/4b^2+1/9c^2=1-m
a+b+c=2m-2 (a+b+c)^2/14=4(m+1)^2/14
a^2+1/4b^2+1/9c^2-(a+b+c)^2/14
=1-m -(m-1))^2 / 7
=-2m^2-3m+5≥0 则求出 -5/2≤m≤1
a^2+1/4b^2+1/9c^2=1-m
a+b+c=2m-2 (a+b+c)^2/14=4(m+1)^2/14
a^2+1/4b^2+1/9c^2-(a+b+c)^2/14
=1-m -(m-1))^2 / 7
=-2m^2-3m+5≥0 则求出 -5/2≤m≤1