请帮我解一道三元一次方程组~~~急用~~~主要是过程.x+Y+z=3.5x/3+y/4+z/5=51/60x/5+y/4+z/3=53.4/60

Question

请帮我解一道三元一次方程组~~~急用~~~主要是过程.
x+Y+z=3.5
x/3+y/4+z/5=51/60
x/5+y/4+z/3=53.4/60

Answer 1

① x+Y+z=3.5
② x/3+y/4+z/5=51/60
③ x/5+y/4+z/3=53.4/60
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①式等号两边同乘15,②式等号两边同乘60,③式等号两边同乘60
得
① 15x+15y+15z=52.5
② 20x+15y+12z=51
③ 12x+15y+20z=53.4
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①-②得④
-5x+3z=1.5 ④
③-②得⑤
-8x+8z=2.4 ⑤
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④式等号两边同乘8 ⑤式等号两边同乘5
得:
-40x+24z=12 ⑥
-40x+40z=12 ⑦
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⑦-⑥
16z=0
得z=0
代入⑥
-40x=12
得:
x=-0.3
由①得:y=3.5-x-z
y=3.8
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x=-0.3
y=3.8
z=0