7x+4y=3640 3x+6y=1560 x=?y=?把每一步的用7意说一下
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7x+4y=3640 3x+6y=1560 x=?y=?把每一步的用7意说一下
7x+4y=3640 3x+6y=1560 x=?y=?
把每一步的用7意说一下
7x+4y=3640 3x+6y=1560 x=?y=?把每一步的用7意说一下
7X+4Y=3640
3X+6Y=1560
相加,得
10X+10Y=5200
左右/10,得
X+Y=520
左右乘3,得
3X+3Y=1560
又3X+6Y=1560
所以:Y=0 X=520
7x+4y=3640 (1)
3x+6y=1560 (2)
由(2)得,x=(1560-6y)/3 (3)
将(3)带入(1)
.....得3640-14y+4y=3640
解得y=0 x=520
7x+4y=3640......(1)
3x+6y=1560......(2)
(1)*3 ---> 21x+12y=10920......(3)
(2)*2 ---> 6x+12y=3120......(4) 注:(3)、(4)两式目的是创造出12y这一公共项,以便消去,求x
(3)-(4) ---> 15x=7800
解得x=520
代入(1)、(2)任意一式,可得y=0
即x=520,y=0
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