设m²+m-1=0,求m³+2m²+3的值

设m²+m-1=0,求m³+2m²+3的值
设m²+m-1=0,求m³+2m²+3的值

设m²+m-1=0,求m³+2m²+3的值
您好：

m²+m-1=0
m²+m=1

m³+2m²+3
=m³+m²+m²+3
=m（m²+m）+m²+3
=m+m²+3
=1+3
=4



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设m²+m-1=0,求m³+2m²+3
因为m²+m-1=0
所以(m²+m-1)(m+1)=0
展开就是m³+2m²-1=0
故:m³+2m²+3=4

m²+m-1=0
m³+2m²+3=m（m²+2m）+3=m(m²+m-1+m+1)+3=m(0+m+1)+3=m²+m+3=m²+m-1+4=4