若把分式2xy分之x y中的x和y都扩大3倍,那么分式值
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2/xy=2(y-x)/xy(y-x)3y/(xy-x^2)=3y^2/xy(y-x)如果不懂,请追问,祝学习愉快!
1/x+1/y=2则(2x+3xy+2y)/(x-xy+y)分子分母同除以xy=(2/x+2/y+3)/(1/x+1/y-1)=(4+3)/(2-1)=7
2(x+3)分之x和(x-3)分之y的乘积
不算,x有可能等于0
xy/(x+y)变为3Xx3Y/(3X+3Y)=3XY/(X+Y)
等于原来分式值的三分之一
200XY/10X+10Y=200(XY)/10(X+Y)所以分式的值扩大了10倍.
正确答案是C.若是3x+4y=0的话,那分式出的就没意义了,考虑问题不要太偏激!那要是你所说,所有的分式分子都为0的话,还不用计算了呢!所以说你那是特殊情况,比如说,我说四边形的四个角是直角,你判断他
因为x+2y=0所以x=-2yxy=(-2y)*y=-2y^2xy+y^2分之x^2-2xy=-y^2分之4y^2+4y^2=-1/8
因为x=3y,所以原式=[(3y)²-3y·y+y²]分之[(3y)²+2·3y·y-3y²]=7y²分之12y²=7分之12
x+2y=0x=-2yxy+y^2分之x^2+3xy=x^2+3xy/xy+y^2=4y^2-6y^2/-2y^2+y^2=-2y^2/-y^2=2
若x+2y=0,xy不等于0,求分式xy+y^2分之x^2+2xy的值x+2y=0,x=-2yx^2+2xy/xy+y^2=(4y^2-4y^2)/xy+y^2=0
3/5再问:详细过程呢再答:y-x=3xyx-y=-3xy代入得:(-6xy+3xy)/(-3xy-2xy)=-3/-5=3/5
y-x=3xyx-y=-3xyx-2xy-y=-5xy2x+3xy-2y=2(x+y)+3xy=-6xy+3xy=-3xy分式x-2xy-y分之2x+3xy-2y=5/3
1/x-1/y=3(y-x)/xy=3y-x=3xy分式的分母=x-2xy-y=(x-y)-2xy=-5xy分子=2x+3xy-2y=2(x-y)+3xy=-3xy所以原式=3/5
原式为2x^2/(x+y)xy都扩大3倍后2(3x)^2/(3x+3y)=18x^2/3(x+y)=6x^2/(x+y)
(Y-X)÷(XY)=3可变形为Y-X=3XY(2X+3XY-2Y)÷(X-2XY-Y)=(2X-2Y+3XY)÷(X-Y-2XY)={2(x-y)+3xy}÷(X-Y-2XY)={2(3xy)+3x
2xy/x+y2x.2y/2x+2y=4xy/2*(x+y)=2xy/x+y不知道对不对