解方程组3(X+Y)-5(X-Y)16 2(X+Y)-1(X-Y)=15

问题描述:

解方程组3(X+Y)-5(X-Y)16 2(X+Y)-1(X-Y)=15

3(X+Y)-5(X-Y)=16
2(X+Y)-1(X-Y)=15
设X+Y=a X-Y=b
则有
3a-5b=16 (1)
2a-b=15 (2)
(1)*2-(2)*3得b=13/7
则a=59/7
则X=36/7 Y=23/7