5x+y=2,x-3y=4,求x和y,
问题描述：
5x+y=2,x-3y=4,求x和y,
答
5x+y=2.①
x-3y=4.②
①x3+②得
15x+3y+x-3y=6+4
16x=10
x=5/8
则y=2-5x=2-25/8= -9/8