x²-4mx+8x+4m²=0,[-(4m-8)]²-16m^2=0 ,16m²-64m+64-16m²=0,m=1
x²+4x+4=0 ,x=-2
x1²+x2²=136
x1+x2=4m-8 ,x1x2=4m² ,
(x1+x2)²=16m²-64m+64 ,136+8m²=16m²-64m+64 ,8m²-64m-72=0 ,m²-8m-9=(m-9)(m+1)=0
m=9,(m=-1舍去)
x²-4mx+8x+4m²=0,[-(4m-8)]²-16m^2=0 ,16m²-64m+64-16m²=0,m=1
x²+4x+4=0 ,x=-2
x1²+x2²=136
x1+x2=4m-8 ,x1x2=4m² ,
(x1+x2)²=16m²-64m+64 ,136+8m²=16m²-64m+64 ,8m²-64m-72=0 ,m²-8m-9=(m-9)(m+1)=0
m=9,(m=-1舍去)