Question

三元一次方程组 x:y=3:4 y:z=4:5 x+y+z=36

Answer 1

由x:y得x=3/4y ,,,同理，，z=5/4y,,,,再都带入第三个方程，，解出y=3,,,其他同理，，，x=9/4,,,,,,z=15/4

Answer 2

x:y=3:4
x=3y/4 (1)
y:z=4:5
z=5y/4 (2)
(1).(2)代入:x+y+z=36
3y/4+y+5y/4=36
3y=36
y=12
x=9
z=15
方程组的解:x=9,y=12,z=15