若y-2x=3,则2（y-2x）^2-4(2x-y)^2-6x+3y的值是? 急啊!若x+5y-4z=6，3x+8y-7z=-4则x+y-z=（ ）观察下列等式：4-1=3,9-4=5,16-9=7,25-16=9，36-25=11.....x这些等式反映了自然数间的某种规侓，设n（n大于.等于1)为自

若x+y=4,则多项式1/2(x+y)+4(x-y)-3（x-y）-3/2(x+y)-x+y值是（） （x+y）/2- x-y/2=6 3(x+y)=4(x-y) 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 若|x-3|+（y+2）=0,则（x-y+4xy/x-y）（x+y-4xy/x+y）的值是 若|x-3|+（y+2）²=0,则（x-y+4xy/x-y）（x+y-4xy/x+y）的值是 若x-y不等于0,2x-3y=0,则分式(10x-11y)/(x-y)的值是（）?(10x-11y)/(x-y) =[(8x-8y)+(2x-3y)]/(x-y) =8为什么8X-8Y=8？(10x-11y)/(x-y)=[(8x-8y)+(2x-3y)]/(x-y)=8+(2x-3y)]/(x-y)=8+0=8 若2x=3y,则(x*x+y*y)/x*x=? (5)若x/2=y/3(y不为0）则x/y=____,x+y/y=___,y/x-y=___. x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 若5x+3y=3x+4y=x+2y+6,则x+y=___ 若x/y=4/3 则3x+2y/2x-5y= 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( )若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( ） 若x,y,z成等差数列,则(z-x)^2-4(x-y)(y-x)= 若实数x,y满足x的平方+y的平方-4x-2y+5=0,则（x+y）/2x-3= 2x-y/x+y=4,则4x-2y/2x+2y+3x+3y/2x-y