Question

若x:y:z=2:3:4且2x+y-z=9,试求2x+3y+z的值

只要列示和结果，不要过程，是三元一次方程组

Answer 1

x:y:z=2:3:4
设x=2k,y=3k,z=4k
∵2x+y-z=9,
∴4k+3k-4k=9
k=3
∴x=6,y=9,z=12
2x+3y+z
=2×6+3×9+12
=51

Answer 2

解：设x=2k，y=3k，z=4k，得
2x+y-z=4k+3k-4k=3k=9,k=3
2x+3y+z=4k+9k+4k=17k=51