3x-5y=6 x-4y=-15
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3x-5y=6 x-4y=-15
解方程组
解方程组
![3x-5y=6 x-4y=-15](/uploads/image/z/4895245-37-5.jpg?t=3x-5y%3D6+x-4y%3D-15)
3x-5y=6 (1)
x-4y=-15 (2)
由(2)得x=4y-15
代入(1)
3(4y-15)-5y=6
12y-45-5y=6
7y=51
y=51/7
x=4y-15=99/7
x-4y=-15 (2)
由(2)得x=4y-15
代入(1)
3(4y-15)-5y=6
12y-45-5y=6
7y=51
y=51/7
x=4y-15=99/7
例X=1 y=21.X+Y=5 X-Y=15 2.2X+3Y=4 5X+6Y=7 3.X+3Y=5 3X+Y=-1 4.
{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
(5x+3y)(3y-5x)-(4x-y)(4y+x)=
6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5
{4/(x+y)+6/(x-y)=3 {9/(x-y)-1/(x+y)=1
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
4x-2y-6y*-y-3x+5y* *=2 就是平方
若5x+3y=3x+4y=x+2y+6,则x+y=___
解方程组 10(x-y)=3(x+y)+15 6(x+y)=4(2x-y)+16