a=0.5,b=-2,所以a的平方+b的平方=17/4
a^2+b^2-a+4b+4+1/4=0a^2-a+1/4+b^2+4b+4=0(a-1/2)^2+(b+2)^2=0a-1/2=0a=1/2b+2=0b=-2a^2+b^2=(1/2)^2+(-2)^2=1/4+4=17/4
