解二元一次方程{(上)3(x+y)-4(x-y)=11(下)2(x-y)+5(x+y)=27.最快最好的给100财富值!
问题描述:
解二元一次方程{(上)3(x+y)-4(x-y)=11(下)2(x-y)+5(x+y)=27.最快最好的给100财富值!
答
3(x+y)-4(x-y)=11(1式子)2(x-y)+5(x+y)=27(2式子)(2式子)*2+(1式子)得13(x+y)=54+11 x+y=5又(1式子)*5-(2式子)*3得15(x+y)-20(x-y)=556(x+y)+15(x+y)=81上下相减得x-y=1所以 x+y=5x-y...