`1,` `(-5/8+6/17).3/2+(-3/8+11/17).3/2`
`=[(-5/8)+6/17+(-3/8)+11/17].3/2`
`=[(-1)+1].3/2=0.3/2=0`
`2,` Đặt `x/5=y/4=z/3=k` `(k∈Z)`
`⇒x=5k; y=4k; z=3k`
Thay `x=5k; y=4k; z=3k` vào `P`, ta có:
`P=(5k+2.4k-3.3k)/(5k-2.4k+3.3k)=(5k+8k-9k)/(5k-8k+9k)=(4k)/(6k)=2/3`
Vậy `P=2/3`.