设集合A={x丨x2+4x=0},B={x丨x2+2(m+1)x+m2-1=0}.若A∩B=B,求m的值?

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设集合A={x丨x2+4x=0},B={x丨x2+2(m+1)x+m2-1=0}.若A∩B=B,求m的值?
设集合A={x丨x2+4x=0},B={x丨x2+2(m+1)x+m2-1=0}.若A∩B=B,求m的值?

设集合A={x丨x2+4x=0},B={x丨x2+2(m+1)x+m2-1=0}.若A∩B=B,求m的值?
A={x丨x^2+4x=0}
={x| x=0 or -4 }
B={x丨x^2+2(m+1)x+m^2-1=0}
if A∩B=B
=> B is subset of A
when x=0
m^2-1 =0
m=1 or -1
when x= -4
16-8(m+1)+ m^2-1 =0
m^2-8m+7=0
m= 1 or 7
ie m =1 or -1 or 7

A:x(x+4)=0
x=0 或 x=-4
A={0,-4}
A∩B=B说明0,-4也是B的元素
0+(-4)=-2(m+1)
m=1
m^2-1=1-1=0成立

m=1