x=2^m+12^m=x-1两边平方,(2^m)^2=(x-1)^24^m=x^2-2x+1所以,y=3+4的m次方=3+x^2-2x+1=x^2-2x+4即,y=x^2-2x+4
y=x的平方-2x+4
