Question

X2+Y2+8X+6Y+25=0 求代数式(x2-4y2/x2+4xy+4y2)-x/x+2y

Answer 1

X2+Y2+8X+6Y+25=0

x^2+y^2+8x+6y+25=0

x^2+8x+16+y^2+6y+9=0

(X+4)^2+(y+3)^2=0

x=-4 y=-3

（x^2-4y^2)/(x^2+4xy+4y^2)-x/x+2y

=(x-2y)(x+2y)/(x+2y)^2-x/x+2y

=(x-2y)/(X+2y)-x/x+2y

=(x-2y-x)/x+2y

=-2y/x+2y

=-2(-3)/(-4)+2(-3)

=6/-10

=-3/5