4(2x+y)-5(2x-y)=3.①
2(2x+y)+10(2x-y)=39.②
①*2:8(2x+y)-10(2x-y)=6.③
②+③:10(2x+y)=45
(2x+y)=4.5
同理:(2x-y)=3
联立得:x=15/8,y=3/4
或 将2x+y和2x-y看做一个整体,设2x+y=a,2x-y=b,
方程缩写为4a-5b=3,2a+10b=39,
解得a=9/2,b=3,
则x=15/8,b=3/4.(这个简单点)
4(2x+y)-5(2x-y)=3.①
2(2x+y)+10(2x-y)=39.②
①*2:8(2x+y)-10(2x-y)=6.③
②+③:10(2x+y)=45
(2x+y)=4.5
同理:(2x-y)=3
联立得:x=15/8,y=3/4
或 将2x+y和2x-y看做一个整体,设2x+y=a,2x-y=b,
方程缩写为4a-5b=3,2a+10b=39,
解得a=9/2,b=3,
则x=15/8,b=3/4.(这个简单点)