1.6x=5y300+4x+100=4y2.4(x+y)=805(x-y)=803.y-x=45(85%y-x)8=(y

来源：学生作业帮编辑：搜搜考试网作业帮分类：数学作业时间：2024/04/29 11:16:02

1.6x=5y
300+4x+100=4y
2.4(x+y)=80
5(x-y)=80
3.y-x=45
(85%y-x)8=(y-35-x)x2
4.0.7(1+40%)x+0.9(1+40%)y=399
(1+40%)x+((1+40%)y=490
5.x+y/2=50
2/3x+y=50
6.x+y=300
2.89%乘3x+2.7%乘3y(1-20%)=32338.2-30000

第一题,由方程式2化简4y－4x=400,y－x=100即y＝100＋x,代入方程1可得,x＝500,y＝600
第二题,将两个方程式化简即x+y=20,x－y=16,两式相加即x=18,y=2
第五题,x+y/2=2/3x+y即得x=3/2y,代入方程式一,可得x＝75／2,y＝25

x-y+5x-4x= ? 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 （5x+3y)(3y-5x)-(4x-y)(4y+x)= 已知：4x = 5y,求(x+y) ：y 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? x2-x-y2-y 解法：=(x2-y2)-(x+y) =(x+y)(x-y)-(x+y) =(x+y)(x-y-1) [(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x= (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai y=x+4/x (x 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y* 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1