Question

已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值?

Answer 1

即(x-2y)²=0

x-2y=0

所以x=2y

所以原式=(2x²+2xy-xy-y²)/(4x²-4xy+y²)

=(2x²+xy-y²)/(4x²-4xy+y²)

=(2x-y)(x+y)/(2x-y)²

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

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

=3y/3y

=1