Question

1-（x-y)/(x-2y)/(x^2-y^2)/(x^2-4xy+4y^2)实数x,y满足|2x-y+1|+2根号下3x-2y+4=0化简求值

Answer 1

|2x-y+1|+2√(3x-2y+4)=0
说明2x-y+1=0 3x-2y+4=0
解得y=2x+1代入右式得3x-2(2x+1)+4=0 -x+2=0 x=2 y=5
代入得1-(2-5)/(2-10)/(4-25)/(4-40+100)=1-(-3)/(-8)/(-21)/64
=1+24/21=2(3/21)=2(1/7)=15/7

Answer 2

∵实数x,y满足|2x-y+1|+2根号下3x-2y+4=0
∴|2x-y+1|=0且2根号下3x-2y+4=0
∴
{2x-y+1=0
{3x-2y+4=0
∴x=2,y=5
故
1-（x-y)/(x-2y)/(x^2-y^2)/(x^2-4xy+4y^2)
=1-（-3）/(-8)/(-10)/64
=-7/5

追问

要先化简再带入求值