S=\frac{2}{1.4.7}+\frac{2}{4.7.10}+…+\frac{2}{34.37.40} 12/08/2021 Bởi Raelynn S=\frac{2}{1.4.7}+\frac{2}{4.7.10}+…+\frac{2}{34.37.40}
Đáp án: tham khảo ạ ≈ Giải thích các bước giải: `S=\frac{2}{1.4.7}+\frac{2}{4.7.10}+…+\frac{2}{34.37.40}` `S=1/1.4 – 1/4.7 + 1/4.7 – 1/7.10+…+1/34.37 – 1/37.40` `S=1/1.4 – 1/37.40` `S=1/4 – 1/1480` `S=369/1480` Bình luận
Đáp án: $\rm S=\dfrac{2}{1.4.7}+\dfrac{2}{4.7.10}+…+\dfrac{2}{34.37.40}\\=\dfrac{1}{1.4}-\dfrac{1}{4.7}+\dfrac{1}{4.7}-\dfrac{1}{7.10}+…..+\dfrac{1}{34.37}-\dfrac{1}{37.40}\\=\dfrac{1}{4}-\dfrac{1}{1480}\\=\dfrac{369}{1480}$ Bình luận
Đáp án:
tham khảo ạ ≈
Giải thích các bước giải:
`S=\frac{2}{1.4.7}+\frac{2}{4.7.10}+…+\frac{2}{34.37.40}`
`S=1/1.4 – 1/4.7 + 1/4.7 – 1/7.10+…+1/34.37 – 1/37.40`
`S=1/1.4 – 1/37.40`
`S=1/4 – 1/1480`
`S=369/1480`
Đáp án:
$\rm S=\dfrac{2}{1.4.7}+\dfrac{2}{4.7.10}+…+\dfrac{2}{34.37.40}\\=\dfrac{1}{1.4}-\dfrac{1}{4.7}+\dfrac{1}{4.7}-\dfrac{1}{7.10}+…..+\dfrac{1}{34.37}-\dfrac{1}{37.40}\\=\dfrac{1}{4}-\dfrac{1}{1480}\\=\dfrac{369}{1480}$