x1-x2+x3=1x2-x3+x4=21若x1,x2,x3,x4,x5满足方程组x3-x4+x5=3x4-x5+x1=4x5-x1+x2=5求x2x3x4的值2已知x1+x4+x6+x7=39x2+x4+x5+x7=49x3+x5+x6+x7=41x4+x7=13x5+x7=14x6+x7=9x1+x2+x3+x4+x5+x6+x7=9求x7的值若x1,x2,x3,x4,x5满足方程组x1-x

Question

x1-x2+x3=1
x2-x3+x4=2
1若x1,x2,x3,x4,x5满足方程组 x3-x4+x5=3
x4-x5+x1=4
x5-x1+x2=5
求x2 x3 x4的值
2已知 x1+x4+x6+x7=39 x2+x4+x5+x7=49 x3+x5+x6+x7=41 x4+x7=13 x5+x7=14 x6+x7=9 x1+x2+x3+x4+x5+x6+x7=9
求x7的值
若x1,x2,x3,x4,x5满足方程组 x1-x2+x3=1 x2-x3+x4=2 x3-x4+x5=3 x4-x5+x1=4
x5-x1+x2=5
求x2 x3 x4的值

Answer 1

1、把x1-x2+x3=1、x2-x3+x4=2、x3-x4+x5=3、x4-x5+x1=4、x5-x1+x2=5全部相加得x1+x2+x3+x4+x5=15.把x1-x2+x3=1、x2-x3+x4=2相加得x1+x4=3,把x2-x3+x4=2、x3-x4+x5=3相加得x2+x5=5,把x3-x4+x5=3、x4-x5+x1=4相加得x3+...