1 thực hiện phép tính tính hợp lí nếu có thee5 a, 3/5+ -2/5 b, 8.5-8.2/16 c, 1/2+1/6+1/12+1/20+1/30+1/24 04/10/2021 Bởi Maya 1 thực hiện phép tính tính hợp lí nếu có thee5 a, 3/5+ -2/5 b, 8.5-8.2/16 c, 1/2+1/6+1/12+1/20+1/30+1/24
Đáp án: `a) 3/5+(-2)/5` `=(3+(-2))/5=1/5` `b) (8.5-8.2)/16=(8.(5-2))/16=(8.3)/(8.2)=3/2` `c) 1/2+1/6+1/12+1/20+1/30+1/42` `=1/(1.2)+1/(2.3)+1/(3.4)+1/(4.5)+1/(5.6)+1/(6.7)` `=1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7` `=1/1-1/7=6/7` Bình luận
`a)“3/5+(-2)/5` `=3/5-2/5` `=1/5` `b)“(8.5-8.2)/16` `=(8(5-2))/16` `=(8.3)/16` `=(cancel(8).3)/(cancel(8).2)` `=3/2` `c)“1/2+1/6+1/12+1/20+1/30+1/42` `=1/(1.2)+1/(2.3)+1/(3.4)+1/(4.5)+1/(5.6)+1/(6.7)` `=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7` `=1-1/7` `=6/7` Bình luận
Đáp án:
`a) 3/5+(-2)/5`
`=(3+(-2))/5=1/5`
`b) (8.5-8.2)/16=(8.(5-2))/16=(8.3)/(8.2)=3/2`
`c) 1/2+1/6+1/12+1/20+1/30+1/42`
`=1/(1.2)+1/(2.3)+1/(3.4)+1/(4.5)+1/(5.6)+1/(6.7)`
`=1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7`
`=1/1-1/7=6/7`
`a)“3/5+(-2)/5`
`=3/5-2/5`
`=1/5`
`b)“(8.5-8.2)/16`
`=(8(5-2))/16`
`=(8.3)/16`
`=(cancel(8).3)/(cancel(8).2)`
`=3/2`
`c)“1/2+1/6+1/12+1/20+1/30+1/42`
`=1/(1.2)+1/(2.3)+1/(3.4)+1/(4.5)+1/(5.6)+1/(6.7)`
`=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7`
`=1-1/7`
`=6/7`