要20道二元一次方程组题和答案

<1>
y=2x-3
3x+2y=8
x=2
y=1
<2>
2x-y=5
3x+4y=2
x=2
y=-1
<3>
2s+3t=-1
4s-3t=8
s=6/7
t=-10/9
<4>
2x-3y=7
x-3y=7
x=0
y=-3/7
<5>
2x+y=5
x-3y=6
x=3
y=-1
<6>
x+3y=7
y-x=1
x=1
y=2
<7>
x+y=4
2x-y=5
x=3
y=1
<8>
7x-7y=-11
7x-2y=-12
x=-1
y=-1
<9>
3x-5y=6
2x-3y=4
x=2
y=0
<10>
x+1=5(y+2)
3(2x-5)-4(y+4)=5
x=4
y=-1
<11>
3y+25=x
4(y-4)=x
x=148
y=41
<12>
x+y+4.2=12.8
2x+1.5y=15
x=5
y=3
<13>
3x-2y=10
5x-4y=-130
x=-10
y=-20
<14>
6x+7y=-19
6x-5y=17
x=1/3
y=-3
<15>
3(x-1)=y+5
5(y-1)=3(x+5)
x=5
t=7
<16>
2(x-y)=2y-x+1
0.5x+0.1y=0.08*50
x=7
y=5
<17>
2(x+2)-3(y-1)=13
3(x+2)+5(y-1)=30.9
x=6.3
y=2.2
<18>
x+y=m
5x-3y=-m
x=m/4
y=3/4m
<19>
x-2y=-3
3x+y=5
x=1
y=2
<20>
x+2(x+2y)=4
x+2y=2
x=0
y=1