x的方程x²+(8-4M)x+4m²=0
判别式=(8-4m)^2-4*1*4m^2
=64-64m+16m^2-16m^2
=64-64m
方程有两个相等的实数根
则有64-64m=0
m=1
x²+(8-4M)x+4m²=0
x²+(8-4*1)x+4*1²=0
x²+4x+4=0
(x+2)^2=0
x=-2
x的方程x²+(8-4M)x+4m²=0
判别式=(8-4m)^2-4*1*4m^2
=64-64m+16m^2-16m^2
=64-64m
方程有两个相等的实数根
则有64-64m=0
m=1
x²+(8-4M)x+4m²=0
x²+(8-4*1)x+4*1²=0
x²+4x+4=0
(x+2)^2=0
x=-2