Thực hiện phép tính a)4/7+-5/8-3/28 b) 9/27+7/-49 c) -1/2+3/7-1/9-7/18+4/7 d) -3/16+(2/3+3/17) 21/09/2021 Bởi Lyla Thực hiện phép tính a)4/7+-5/8-3/28 b) 9/27+7/-49 c) -1/2+3/7-1/9-7/18+4/7 d) -3/16+(2/3+3/17)
đáp án : a) 4/7+3/28-5/8 b) 9/27+7/-49 c) -1/2+3/7-1/9-7/18+4/7 = 16/28+3/28-5/8 = 9/27+-7/49 =[-1/2-7/18]+[3/7+4/7]-1/9 = 19/28-5/8 = 449/1323+(-189)/1323 =[-9/18-7/18]+[3/7+4/7]-1/9 = 38/56-35/56 = 260/1323 =-16/18+1-1/9 = 33/56 =-16/18+[9/9-1/9] = -16/18+8/9 = -16/18+16/18 = 0 Bình luận
Tham khảo `a) \frac{4}{7}-\frac{5}{8}-\frac{3}{28}` `=\frac{32-35-6}{56}=\frac{-9}{56}` `b) \frac{9}{27}-\frac{7}{49}` `=\frac{1}{3}-\frac{1}{7}` `=\frac{7-3}{21}=\frac{4}{21}` `c) \frac{-1}{2}+\frac{3}{7}-\frac{1}{9}-\frac{7}{18}+\frac{4}{7}` `=(\frac{-1}{2}-\frac{1}{9}-\frac{7}{18})+(\frac{3}{7}+\frac{4}{7})` `=-1+1=0` `d) \frac{-3}{16}+(\frac{2}{3}+\frac{3}{17})` `=\frac{-3}{16}+\frac{43}{51}` `=\frac{535}{816}` `\text{©CBT}` Bình luận
đáp án : a) 4/7+3/28-5/8 b) 9/27+7/-49 c) -1/2+3/7-1/9-7/18+4/7
= 16/28+3/28-5/8 = 9/27+-7/49 =[-1/2-7/18]+[3/7+4/7]-1/9
= 19/28-5/8 = 449/1323+(-189)/1323 =[-9/18-7/18]+[3/7+4/7]-1/9
= 38/56-35/56 = 260/1323 =-16/18+1-1/9
= 33/56 =-16/18+[9/9-1/9]
= -16/18+8/9
= -16/18+16/18
= 0
Tham khảo
`a) \frac{4}{7}-\frac{5}{8}-\frac{3}{28}`
`=\frac{32-35-6}{56}=\frac{-9}{56}`
`b) \frac{9}{27}-\frac{7}{49}`
`=\frac{1}{3}-\frac{1}{7}`
`=\frac{7-3}{21}=\frac{4}{21}`
`c) \frac{-1}{2}+\frac{3}{7}-\frac{1}{9}-\frac{7}{18}+\frac{4}{7}`
`=(\frac{-1}{2}-\frac{1}{9}-\frac{7}{18})+(\frac{3}{7}+\frac{4}{7})`
`=-1+1=0`
`d) \frac{-3}{16}+(\frac{2}{3}+\frac{3}{17})`
`=\frac{-3}{16}+\frac{43}{51}`
`=\frac{535}{816}`
`\text{©CBT}`