Question

若|x-3| (y-1)^2=0求多项式5x^2 2y 1-2(x^2 5y-1)

Answer 1

|x-2|>=0

(x-y-1)^2>=0

而,|x-2|+(x-y-1)^2=0

所以|x-2|=0,

(x-y-1)^2=0

得,x=2,y=1

带入得,原式=-7 选A