Question

已知：x的平方加y的平方再减2x,再加4y,再加5,等于零.求x,y的值

Answer 1

2+y~2-2x+4y+5=0

(x-1)~2+(y+2)~2=0

(x-1)~2=0 (y+2)~2=0

x=1 y=-2