Question

解方程组3分之x-y=2分之x+y；2x-5y=7

Answer 1

将3分之x-y=2分之x+y化简为2(x-y)=3(x+y)所以x=-5y代入2式有-15y=7所以y=-7/15故x＝7/3所以x=7/3，y＝-7/15

Answer 2

去分母得2(x-y)=3(x+y) 2x-2y=3x+3y x= - 5y 将x= - 5y代入2x-5y=7得2*（-5y)-5y=7 -10y-5y=7 y= - 7/15 x=-5*(-7/15)=7/3

Answer 3

方程组：｛3分之x+y+2分之x-y=6，①｛3(x+y)-2(x-y)=28，②