EX.
y=2x-1
x+y=8
x+(2x-1)=8
3x=9
x=3,
y=2*3-1=5
x=3,y=5
so
y=x+3
x+y=1
問
x=?,y=?
maths問題
2007-12-02 3:30 am
回答 (4)
2007-12-02 7:26 am
y=x+3--------------------eqn1
x+y=1--------------------eqn2
put eqn 1 into eqn2
x+(x+3) = 1
2x+3 = 1
2x = 1-3
2x = -2
x = -1
put x = -1 into eqn 1
y= -1+3
y = 2
so we got the ans x = -1 and at the same time y = 2
x+y=1--------------------eqn2
put eqn 1 into eqn2
x+(x+3) = 1
2x+3 = 1
2x = 1-3
2x = -2
x = -1
put x = -1 into eqn 1
y= -1+3
y = 2
so we got the ans x = -1 and at the same time y = 2
2007-12-02 3:58 am
x=-1 y=2
2007-12-02 3:45 am
y=x+3...........1
x+y=1.........2
y=1---x.........3
把3代入1
y=x+3
1---x=x+3
-2=2x
x=-1
把x=-1代入2
-1+y=1
y=2
x=-1 y=2
x+y=1.........2
y=1---x.........3
把3代入1
y=x+3
1---x=x+3
-2=2x
x=-1
把x=-1代入2
-1+y=1
y=2
x=-1 y=2
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