1. {3x+2y=5
5x-y=4 /×2
{3x+2y=5
10x-2y=8
---------------( + )
11x=13
x=13/11
{x=13/11
3x+2y=5
{x=13/11
3×13+22y=55
{x=13/11
39+22y=55
{x=13/11
22y=16
{x=13/11
y=16/22
{x=13/11
y=8/11
2.x=1
y=-2
deci
{1+a×(-2)=13
b-3×(-2)=12
{1-2a=13
b+6=12
{-2a=12
b=6
{a=-6
b=6