解方程组:{二分之x+y+二分之x-y=6,4(x+y)-5(x-y)=2()
问题描述:
解方程组:{二分之x+y+二分之x-y=6,4(x+y)-5(x-y)=2()
答
设(x+y)为t,(x-y)为p,所求的解为c
所以t/2+p/2=6
4t-5p=c
整理得:5t+5p=60
4t-5p=c
两式相加得9t=60+c
c=9t-60
所以4(x+y)-5(x-y)=9(x+y)-60