韦达定理
x1+x2=4/m
x1x2=-35/m
(x1-x2)²=36
即(x1+x2)²-4x1x2=36
16/m²+140/m-36=0
8(1/m)²+70(1/m)-18=0
(4/m-1)(2/m+18)=0
1/m=1/4,1/m=-9
m=4,m=-1/9