快遞百科

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標題:

method of elimination~20points

發問:

1.25y-0.75z=1 0.25y+1.25z=17 3c+2d+4=2c-3d+7=0 5x=2x-2y+13=3y+9

最佳解答:

1. 1.25y-0.75z=1 => 5y-3z-4=0 ---(1) 0.25y+1.25z=17 => y+5z-68=0 ---(2) (1)x5+(2)x3: 5(5y-3z-4)+3(y+5z-68)=0 28y-224=0 y=8 ---(3) Sub. (3) into (1): 5(8)-3z-4=0 3z=36 z=12 2. 3c+2d+4=0 ---(1) 2c-3d+7=0 ---(2) (1)x3+(2)x2: 3(3c+2d+4)+2(2c-3d+7)=0 13c+26=0 c=-2 ---(3) Sub. (3) into (1): 3(-2)+2d+4=0 2d=2 d=1 3. 5x=2x-2y+13 => 3x+2y-13=0 ---(1) 5x=3y+9 => 5x-3y-9=0 ---(2) (1)x3+(2)x2: 3(3x+2y-13)+2(5x-3y-9)=0 19x-57=0 x=3 ---(3) Sub. (3) into (1): 3(3)+2y-13=0 2y=4 y=2

其他解答:C8D74AB62542840B