这个二元一次方程怎么解2x / 3 + 3y / 4 = 1 / 5 ,(1)5x / 6 - 5y / 2 = 2 .(2)(1)式等号两边同时乘于60得 40x + 45y = 12 ,(3)(2)式等号两边同时乘于6得5x - 15y = 12 .(4)(4)式等号两边同时乘于3得15x - 45y = 36 .(5)(5)
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![这个二元一次方程怎么解2x / 3 + 3y / 4 = 1 / 5 ,(1)5x / 6 - 5y / 2 = 2 .(2)(1)式等号两边同时乘于60得 40x + 45y = 12 ,(3)(2)式等号两边同时乘于6得5x - 15y = 12 .(4)(4)式等号两边同时乘于3得15x - 45y = 36 .(5)(5)](/uploads/image/z/932179-67-9.jpg?t=%E8%BF%99%E4%B8%AA%E4%BA%8C%E5%85%83%E4%B8%80%E6%AC%A1%E6%96%B9%E7%A8%8B%E6%80%8E%E4%B9%88%E8%A7%A32x+%2F+3+%2B+3y+%2F+4+%3D+1+%2F+5+%2C%281%295x+%2F+6+-+5y+%2F+2+%3D+2+.%282%29%281%29%E5%BC%8F%E7%AD%89%E5%8F%B7%E4%B8%A4%E8%BE%B9%E5%90%8C%E6%97%B6%E4%B9%98%E4%BA%8E60%E5%BE%97+40x+%2B+45y+%3D+12+%2C%283%29%282%29%E5%BC%8F%E7%AD%89%E5%8F%B7%E4%B8%A4%E8%BE%B9%E5%90%8C%E6%97%B6%E4%B9%98%E4%BA%8E6%E5%BE%975x+-+15y+%3D+12+.%284%29%284%29%E5%BC%8F%E7%AD%89%E5%8F%B7%E4%B8%A4%E8%BE%B9%E5%90%8C%E6%97%B6%E4%B9%98%E4%BA%8E3%E5%BE%9715x+-+45y+%3D+36+.%285%29%285%29)
这个二元一次方程怎么解2x / 3 + 3y / 4 = 1 / 5 ,(1)5x / 6 - 5y / 2 = 2 .(2)(1)式等号两边同时乘于60得 40x + 45y = 12 ,(3)(2)式等号两边同时乘于6得5x - 15y = 12 .(4)(4)式等号两边同时乘于3得15x - 45y = 36 .(5)(5)
这个二元一次方程怎么解
2x / 3 + 3y / 4 = 1 / 5 ,(1)
5x / 6 - 5y / 2 = 2 .(2)
(1)式等号两边同时乘于60得
40x + 45y = 12 ,(3)
(2)式等号两边同时乘于6得
5x - 15y = 12 .(4)
(4)式等号两边同时乘于3得
15x - 45y = 36 .(5)
(5)式 + (3)式 = (15x - 45y) + (40x + 45y) = 36 + 12
15x - 45y + 40x + 45y = 48
55x = 48
x = 48 / 55
y 怎样算出 y
这个二元一次方程怎么解2x / 3 + 3y / 4 = 1 / 5 ,(1)5x / 6 - 5y / 2 = 2 .(2)(1)式等号两边同时乘于60得 40x + 45y = 12 ,(3)(2)式等号两边同时乘于6得5x - 15y = 12 .(4)(4)式等号两边同时乘于3得15x - 45y = 36 .(5)(5)
X带入(4),48/11-15y=12; 15y=48/11-132/11; 15y=-84/11; y= -84/165.y是负数
把 x = 48 / 55代入2x / 3 + 3y / 4 = 1 / 5 , (1)就可以解出y
把x值代入1中即可求出y