3x+3y+2x-2y=36,4x+4y-5x+5y=2的解用二元一次方程组
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3x+3y+2x-2y=36,4x+4y-5x+5y=2的解用二元一次方程组
3x+3y+2x-2y=36,4x+4y-5x+5y=2的解
用二元一次方程组
3x+3y+2x-2y=36,4x+4y-5x+5y=2的解用二元一次方程组
3x+3y+2x-2y=3 5x+y=3①
4x+4y-5x+5y=2 -x+9y=2②
①+②*5得46y=13 y=13/46
带入②得x=-2+117/46=25/46
所以x=25/46
y=13/46
3x+3y+2x-2y=36.........①
4x+4y-5x+5y=2..........②
①简化
5x+y=36................③
②简化
-x+9y=2................④
④*5+③
46y=46
y=1....................⑤
将⑤带入③
5x+1=36
5x=35
x=7
解为:x=7 y=1
即方程5x+y=36和方程-x+9y=2组成的方程组的解.第二个方程两边乘以5加到第一个方程上.解得46y=46即y=1,所以由方程二,x=7
3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2
(x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)=
2(x+y)-3(x-y)=3 ,4(x+y)+3(x-y)=15
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20
{(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6
3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9
(x+y)/2- x-y/2=6 3(x+y)=4(x-y)
x+y/3+x-y/2=6 4(x+y)-2(x-y)=40
4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5
(x+3y-4)(2x-y)
计算(2x-3y)(x+4y)-(3x+y)(x-2y)(2x-3y)(x+4y)-(3x+y)(x-2y)
已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y
因式分解(x-2y)(x-3y)+(x-4y)(x-5y)+(x-3y)(x-5y)+(x-2y)(x-4y)
x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=?