Đáp án:
`a)-1/3`
`b)1/24`
`c)5/6`
Giải thích các bước giải:
`a)-2/14+(-8)/24+6/42`
`=(-2.12)/(14.12)+(-8.7)/(24.7)+(6.4)/(42.4)`
`=-24/168+(-56)/168+24/168`
`=(-24-56+24)/168`
`=((-24+24)-56)/168`
`=-56/168`
`=(-56:56)/(168:56)`
`=-1/3`
`b)5/8+3/12+(-5)/6`
`=(5.3)/(8.3)+(3.2)/(12.2)+(-5.4)/(6.4)`
`=15/24+6/24+(-20)/24`
`=(15+6-20)/24`
`=(21-20)/24`
`=1/24`
`c)-2/17+4/19+(-15)/17+15/19+5/6`
`=(-2/17+(-15)/17)+(4/19+15/19)+5/6`
`=(-2-15)/17+(4+15)/19+5/6`
`=-17/17+19/19+5/6`
`=-1+1+5/6`
`=0+5/6`
`=5/6`
