Question

设m的平方+m-1=0,求m的3次方+2m的平方+3的值

Answer 1

由m^2+m-1=0,得：m^2=1-m,

m^3+2m^2+3

= m^2*m+2(1-m)+3

= (1-m)*m+2(1-m)+3

= -m^2-m+5

= -(m^2+m-1)+4

= 4