A= $\frac{4}{21}$ +$\frac{4}{77}$ +$\frac{4}{165}$ +$\frac{4}{285}$ +$\frac{4}{437}$ +$\frac{4}{621}$ 01/09/2021 Bởi Alexandra A= $\frac{4}{21}$ +$\frac{4}{77}$ +$\frac{4}{165}$ +$\frac{4}{285}$ +$\frac{4}{437}$ +$\frac{4}{621}$
Bài làm : `A=4/21+4/77+4/165+4/285+4/437+4/621` `A=4/(3.7)+4/(7.11)+4/(11.15)+4/(15.19)+4/(19.23)+4/(23.27)` `A=1/3-1/7+1/7-1/11+1/11-1/15+1/15-1/19+1/19-1/23+1/23-1/27` `A=1/3+(-1/7+1/7)+(-1/11+1/11)+(-1/15+1/15)+(-1/19+1/19)+(-1/23+1/23)-1/27` `A=1/3+0+0+0+0+0-1/27` `A=1/3-1/27` `A=9/27-1/27` `A=8/27` Bình luận
Đáp án: `A=8/27` Giải thích các bước giải: `A=4/21+4/77+4/165+4/285+4/437+4/621` `A=4/3.7+4/7.11+4/11.15+4/15.19+4/19.23+4/23.27` `A=1/3-1/7+1/7-1/11+1/11-1/15+1/15-1/19+1/19-1/23+1/23-1/27` `A=1/3-1/27` `A=8/27` Bình luận
Bài làm :
`A=4/21+4/77+4/165+4/285+4/437+4/621`
`A=4/(3.7)+4/(7.11)+4/(11.15)+4/(15.19)+4/(19.23)+4/(23.27)`
`A=1/3-1/7+1/7-1/11+1/11-1/15+1/15-1/19+1/19-1/23+1/23-1/27`
`A=1/3+(-1/7+1/7)+(-1/11+1/11)+(-1/15+1/15)+(-1/19+1/19)+(-1/23+1/23)-1/27`
`A=1/3+0+0+0+0+0-1/27`
`A=1/3-1/27`
`A=9/27-1/27`
`A=8/27`
Đáp án:
`A=8/27`
Giải thích các bước giải:
`A=4/21+4/77+4/165+4/285+4/437+4/621`
`A=4/3.7+4/7.11+4/11.15+4/15.19+4/19.23+4/23.27`
`A=1/3-1/7+1/7-1/11+1/11-1/15+1/15-1/19+1/19-1/23+1/23-1/27`
`A=1/3-1/27`
`A=8/27`