解二元一次方程组3(x+y)-4(x-y)=4 x+y/2+x-y/6=1
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解:3(x + y) - 4(x - y) = 4 ①
x + y/2 + x - y/6 = 1 ②
顷慎 由①得
7y - x = 4 ③
由②得
2x + y/2 - y/6 = 1
2x + 3y/6 - y/6 = 1
2x - y/6 = 1
12x - y = 6 ④
③ + ④ × 7得
83x = 46
x = 46/83
把 x = 46/83代入 ③得
7y - 46/83 = 4
7y = 4 + 46/83
7y = 378/83
y = 378/581
∴ 原方程组的解为
x = 46/83
y = 378/581
如果原雀返敬方程是“3(x + y) - 4(x - y) = 4 x + y)/2 + (x - y)/6 = 1 ”的话,可以作如下解答。
解:世空 3(x + y) - 4(x - y) = 4 ①
(x + y)/2 + (x - y)/6 = 1 ②
② × 6得
3(x + y) + (x - y) = 6 ③
③ - ①得
5(x - y) = 2
x - y = 2/5 ④
把x - y = 2/5代入①得
3(x + y) - 4 × 2/5 = 4
3(x + y) = 48/5
x + y = 16/5 ⑤
④ + ⑤得
2x = 18/5
x = 9/5
把x = 9/5代入 ④得
9/5 - y = 2/5
y = 9/5 - 2/5
y = 7/5
∴ 原方程组的解为
x = 9/5
y = 7/5
x + y/2 + x - y/6 = 1 ②
顷慎 由①得
7y - x = 4 ③
由②得
2x + y/2 - y/6 = 1
2x + 3y/6 - y/6 = 1
2x - y/6 = 1
12x - y = 6 ④
③ + ④ × 7得
83x = 46
x = 46/83
把 x = 46/83代入 ③得
7y - 46/83 = 4
7y = 4 + 46/83
7y = 378/83
y = 378/581
∴ 原方程组的解为
x = 46/83
y = 378/581
如果原雀返敬方程是“3(x + y) - 4(x - y) = 4 x + y)/2 + (x - y)/6 = 1 ”的话,可以作如下解答。
解:世空 3(x + y) - 4(x - y) = 4 ①
(x + y)/2 + (x - y)/6 = 1 ②
② × 6得
3(x + y) + (x - y) = 6 ③
③ - ①得
5(x - y) = 2
x - y = 2/5 ④
把x - y = 2/5代入①得
3(x + y) - 4 × 2/5 = 4
3(x + y) = 48/5
x + y = 16/5 ⑤
④ + ⑤得
2x = 18/5
x = 9/5
把x = 9/5代入 ④得
9/5 - y = 2/5
y = 9/5 - 2/5
y = 7/5
∴ 原方程组的解为
x = 9/5
y = 7/5
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