Y&A (X+Y)*(5/2)=1200 (X-Y)*(10/3)=1200

(X+Y)*(5/2)=1200 (X-Y)*(10/3)=1200  

(X+Y)*(5/2)=1200 (X-Y)*(10/3)=1200

(x+y)*(5/2)=1200
x+y=1200除以（5/2）
x+y=480【①】
(X-Y)*(10/3)=1200
x-y=1200除以（10/3）
x-y=360【②】
①+②=2x=840
x=420
①-②=2y=120
y=60
∴x=420,y=60
是二元一次方程组吧

5/2（x+y）=1200 11/3（x-y）=1200 求解

解：化简得
{x+y=480①
{x-y=3600/11②
把①+②得
x=4440/11
代入①得y=840/11
不懂，请追问，祝愉快

5/2(x+y)=1200,10/3(x-y)=1200这个方程组怎么解？

5/2(x+y)=1200,10/3(x-y)=1200;x+y=1200(2/5)=480 为（1）,x-y=1200(3/10)=360,为（2）；(1)+(2):2x=840,x=420;y=60.

5/12[-3/4(x-y)^3]*(x+y)^2*(-x-y)^3*5/6(y-x)^2

原式=4a(a+1)/a(a+2)-a(a-4)/(a+2)2
=4(a+1)/(a+2)-a(a-4)/(a+2)2
=(4a+4)(a+2)-a(a-4)]/(a+2)2
=(3a2+16a+8)/(a+2)2

（x-y)^9/(y-x)^8+(-x-y)^5/(x+y)^4 =(x-y)+(-x-y)^5/(x+y)^4 =(x-y)+[-(x+y)]^5/(x+y)^4 =(x-y)+[-(x+y)]

（x-y)^9/(y-x)^8+(-x-y)^5/(x+y)^4
=(x-y)+(-x-y)^5/(x+y)^4
=(x-y)+[-(x+y)]^5/(x+y)^4
=(x-y)+[-(x+y)]
=-2y
你做的很好啊!
或者这样做：
（x-y)^9/(y-x)^8+(-x-y)^5/(x+y)^4
=(x-y)^9/(x-y)^8+(-x-y)^5/(-x-y)^4
=(x-y)+(-x-y)
=-2y

解方程组:2/(x+y)+5/(x-y)=18 9/(x+y)-10/(y-x)=66

2/(x+y)+5/(x-y)=18
9/(x+y)-10/(y-x)=66
设x+y=a,x-y=b，原方程化为
2/a+5/b=18 -----1(1)
9/a+10/b=66 -------(2)
(2)-(1)*2 得5/a=30 所以a=1/6 ；代入(1)式得b =5/6

即原方程的角是
x=1/2
y=-1/3

则2a+5b=18；9a+10b=66；

解得a=6，b=6/5；

即                           1/（x+y）=6

1/  (x-y)=6/5

故                     x+y=1/6

x-y=5/6

解得         x=1/2

y=-1/3

打字打得不容易，记得给好评哦！

解分式方程：10/(x+y)+3/(x-y)=-5,15/(x+y)-2/(x-y)=-1

设
1/(x+y)=u
1/(x-y)=v
解方程组
10u+3v=-5
15u-2v=-1
u=-0.2
v=-1
x+y=-5
x-y=-1
然后解得
x=-3
y=-2

5/12(x+y)^2·(-x-y)^3·(-3/4(x-y)^3)·6/5(y-x)^2

=(5/12)*(-1)^3*(-3/4)*(6/5)*(x+y)^5*(x-y)^5
=3/8*(x^2-y^2)^5
=0.375x^10-1.875x^8*y^2+3.75x^6*y^4-3.75x^4*y^6+1.875x^2*y^8-0.375y^10

2/(x+y)+5/(x-y)=-8, 9/(x+y)-10/(x-y)=-11 谁会做 他舅近来帮忙下

1/(x+y)=a
1/(x-y)=b
则2a+5b=-8 (1)
9a-10b=-11 (2)
(1)*2+(2)
13a=-27
a=-27/13
b=-1194/65
所以
x+y=-13/27
x-y=-65/1194
相加，求出x
相减，求出y