Hãy luôn nhớ cảm ơn và vote 5*
nếu câu trả lời hữu ích nhé!
Đáp án: + Giải thích các bước giải:
Bài `47:`
`a,`.
`7``3/5-(``2``5/7+5``3/5)`.
`=38/5-(19/7+28/5)`.
`=38/5-19/7-28/5`.
`=38/5-28/5-19/7`.
`=2-19/7`
`=-5/7`.
`b,`.
`8``2/7-(``3``4/9+4``2/7)`.
`=58/7-(31/9+30/7)`.
`=58/7-31/9-30/7`.
`=58/7-30/7-31/9`.
`=4-31/9`.
`=5/9`.
`c,`.
`8``2/9-(``4``2/9-5``1/2)`.
`=74/9-(38/9-11/2)`.
`=74/9-38/9+11/2`.
`=4+11/2`.
`=19/2`.
Bài `48:`.
`a,`.
`6``2/5-(``2``4/9+4``2/5)`.
`=32/5-(22/9+22/5)`.
`=32/5-22/9-22/5`.
`=32/5-22/5-22/9`.
`=2-22/9`.
`=-4/9`.
`b,`.
`(6``5/7+2``7/9)-4``5/7`.
`=47/7+25/9-33/7`.
`=47/7-33/7+25/9`.
`=2+25/9`.
`=43/9`.
`c,`.
`(7``8/9+2``3/13)-4``8/9`.
`=(71/9+29/13)-44/9`.
`=71/9+29/13-44/9`.
`=71/9-44/9+29/13`.
`=3+29/13`.
`=68/13`.
Bài `49:`.
`a,`.
`1/6-[1/6-(1/4+9/12)]`.
`=1/6-1/6+(1/4+9/12)`.
`=(1/6-1/6)+(1/4+9/12)`.
`=0+1`.
`=1`.
`b,`.
`2/3-[(-7)/4-(1/2+3/8)`.
`=2/3-[(-7)/4-7/8]`.
`=2/3-(-21/8)`.
`=79/24`.
Bài `50:`.
`a,`.
`3/2-[(-4/7)-(1/2+5/8)]`.
`=3/2-[(-4/7)-9/8]`.
`=3/2-(-95/56)`.
`=179/56`
`b,`.
`-1/24-[1/4-(1/2-7/8)]`.
`=-1/24-[1/4-(-3/8)]`.
`=-1/24-5/8`.
`=-2/3`.
Bài `51:`.
`a,`.
`(13/23+(-15)/4)+(10/23-1/4-2/27)`.
`=13/23+(-15)/4+10/23-1/4-2/27`.
`=(13/23+10/23)+((-15)/4-1/4)-2/27`.
`=1+(-4)-2/27`.
`=-3-2/27`.
`=-83/27`.
`b,`.
`1/2+(16/21+27/13)-(14/12-5/21)`.
`=1/2+16/21+27/13-14/12+5/21`.
`=(1/2-14/12)+(16/21+5/21)+27/13`.
`=-2/3+1+27/13`.
`=1/3+27/13`.
`=94/39`.
Hãy giúp mọi người biết câu trả lời này thế nào?
Bảng tin