kȡʲôֵʱⷽõxyֵ1С12С1-꼶ѧ
kȡʲôֵʱⷽõxyֵ 1С1 2С1 |
⣺ĽΪ 1 x<1y<1 k<-1 2 x1y1 k3 |
רȨ⡰kȡʲôֵʱⷽõxyֵ1С12С1..Ҫ ԪһηĽⷨ ȿ⡣Щġ£
ԪһηĽⷨ
ƣԪһηĽⷨ
- ԪһηĽ⣺
ʹԪһη̶һδֵ֪Ľ⣬һ - Ԫһη
һأʹԪһηߵֵȵδֵ֪ԪһηĽ⡣ĽḶ́ⷽ顣һ˵һԪһη⣬ԪһηĽ
1һ⡣緽:
x+y=5
6x+13y=89
x=-24/7
y=59/7 ΪĽ
2⡣緽飺
x+y=6
2x+2y=12
Ϊʵһ̣ȵʵԴ⡣
3⡣緽飺
x+y=4
2x+2y=10ڣ
Ϊ̢ڻΪ
x+y=5
뷽̢ìܣԴ⡣
ͨϵ֮ж϶ԪһηĽйx,yĶԪһη飺
ax+by=c
dx+ey=f
a/db/e ʱ÷һ⡣
a/d=b/e=c/f ʱ÷⡣
a/d=b/ec/f ʱ÷⡣ - ԪһηĽⷨ
̵ⷽݡʽ
1a=ba+c=b+c
2a=bac=bc (c>0)
һԪ
1Ԫ
ôԪһ㲽ǣ
ѡһϵȽϼķ̽бΣ y = ax +b x = ay + bʽ
ڽy = ax + b x = ay + bһ̣ȥһδ֪Ӷһ̱һԪһη̣
۽һԪһη̣ x y ֵ
ܽ x y ֵ뷽еһ̣y = ax +b x = ay + bһδ֪
ݰõδֵ֪ôǶԪһη̵Ľ⡣
ⷽ
x+y=5
6x+13y=89
⣺ɢٵ
x=5-y
Ѣ۴ڣ
6(5-y)+13y=89
y=59/7
y=59/7ۣ
x=5-59/7
x=-24/7
x=-24/7
y=59/7 ΪĽ
ǰͨ롱ȥһδ֪ӶĽķԪƴ뷨
2ӼԪ
üӼԪһ㲽Ϊ
ڶԪһηУͬһδ֪ϵͬΪ෴ֱӣȥһδ֪
ڶԪһηУڢеѡһʵȥ˷̵ߣʹһδ֪ϵͬΪ෴
ٰѷ߷ֱӣȥһδ֪õһԪһη̣
۽һԪһη̣
ܽһԪһη̵ĽԭϵȽϼķ̣һδֵ֪
ݰõδֵ֪ôǶԪһηĽ⡣
ⷽ飺
x+y=9
x-y=5
⣺+
2x=14
x=7
x=7٣
7+y=9
⣬ãy=2
x=7
y=2 ΪĽ
õʽʹеijһδ֪ǰϵľֵȣȻӣȥδ֪ʹֻһδ֪⡣ֽԪһηķӼԪƼӼ
3Ӽ-ʹõķ
ⷽ飺
13x+14y=41
14x+13y=40
⣺-ٵ
x-y=-1
x=y-1
Ѣ ٵ
13(y-1)+14y=41
13y-13+14y=41
27y=54
y=2
y=2۵
x=1
ԣx=1,y=2
ص㣺ӼxyýĴԪ
Ԫ
ⷽ飺
x+5)+(y-4)=8
x+5)-(y-4)=4
x+5=m,y-4=n
ԭ̿дΪ
m+n=8
m-n=4
m=6,n=2
x+5=6,y-4=2
x=1,y=6
ص㣺жͬĴʽеx+5,y-4֮࣬ԪɼҲҪԭ
ⷽ飺
x:y=1:4
5x+6y=29
x=ty=4t
2дΪ5t+64t=29
29t=29
t=1
x=1y=4
ġͼ
Ԫһη黹ͼķӦԪһη̸дһκıʽͬϵڻͼ
ֱߵĽ꼴ԪһηĽ⡣
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[ʦ] ʮȫ̳иУ (2018-11-07) |
[ʦ] ̰С (2018-11-07) |
[ʦ] δ (2018-11-07) |