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xy y 2xy 3x y y 2y 1

您好: 1/x-1/y=-1 (y-x)/xy=-1 x-y=xy (3x-2xy-3y)/(2x+xy-2y) =[3(x-y)-2xy]/[2(x-y)+xy] =(3xy-2xy)/(2xy+xy) =xy/3xy =1/3 如果本题有什么不明白可以追问,如果满意请点击“采纳为满意回答” 如果有其他问题请采纳本题后另发点击向我求助,答...

解: 1/x -1/y=2 (y-x)/(xy)=2 y-x=2xy x-y=-2xy (2x-3xy-2y)/(3x+4xy-3y) =[2(x-y)-3xy]/[3(x-y)+4xy] =[2·(-2xy)-3xy]/[3·(-2xy)+4xy] =(-7xy)/(-2xy) =7/2

解:已知x分之1-y分之1=2, 得xy分之y-xy分之x=2 xy分之(y-x)=2 y-x=2xy x-y=-2xy 得(x-xy-y)分之(3x-2xy-3y) =[(x-y)-xy]分之[(3x-3y)-2xy] =[(x-y)-xy]分之[3×(x-y)-2xy] =(-2xy-xy)分之[3×(-2xy)-2xy] =(-3xy)分之(-6xy...

(1) (x-y)(x^2-xy+y^2)+xy(y-x) =(x-y)(x^2-xy+y^2)-xy(x-y) =(x-y)(x^2-xy+y^2-xy) =(x-y)(x^2-2xy+y^2) =(x-y)(x-y)^2 =(x-y)^3 (2)-2xy-4x^2y+2xy^2 =-2xy(1+2x-y) (3)3x^2(a+3)-4x^2y(a+3) =x^2(a+3)(3-4y) a^2-3a+2 =(a-2)(a-1)

3x + 2y = m + 1 ① 4x + 3y = m - 1 ② 3×① - 2×②得到:3(3x + 2y) - 2(4x + 3y ) = 3(m + 1) - 2(m - 1) x = m + 5 ③ ③代入①或者②得到:y = - m - 7 ④ 根据已知 2x +3 y>0 即 2m+10-3m-21 > 0 -m -11> 0 m < - 11

x^2+2xy+2y^2+3x=0 xy+y^2+3y+1=0 即:6y=x^2+3x-2 即:x^2+3x+x(x^2+3x-2)/3+(x^2+3x-2)^2/18=0 化简得:x^4+12x^3+41x^2+30x+4=0 即:x^4+6x^3+x^2+6x^3+36x^2+6x+4x^2+24x+4=0 即:x^2(x^2+6x+1)+6x(x^2+6x+1)+4(x^2+6x+1)=0 即:(x^2+6x+1)(...

2(3x2-2xy+4y2)-3(2x2-xy+2y2),=6x2-4xy+8y2-(6x2-3xy+6y2),=6x2-4xy+8y2-6x2+3xy-6y2,=-xy+2y2;当x=2,y=-1时,原式=-2×(-1)+2×(-1)2=2+2=4.

(1)3x2(2x2-4x+5)=6x4-12x3+15x2;(2)[(-3xy)2x3-2x2(3xy2)312y]÷9x4y2=[9x2y2?x3-2x2?27x3y6?12y]÷9x4y2=[9x5y2-27x5y7]÷9x4y2=x-3xy5.

3x2-2xy+12y2=47① 2x2+xy+8y2=36② ①*36-②*47,得14x^2-119xy+56y^2=0, 2x^2-17xy+8y^2=0, (x-8y)(2x-y)=0, ∴x=8y,③或y=2x④ 由①③解得(x,y)=(4,1/2),(-4,-1/2); 由①④解得(x,y)=(1,2),(-1,-2). ∴x^2+4y^2=17, x^2-4y^2=土15, 于是x^4-16y^4=土255.

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