Tính giá trị biểu thức
E = $\frac{1}{7}$ + $\frac{1}{91}$ +$\frac{1}{247}$ + $\frac{1}{415}$ + $\frac{1}{475}$ + … +$\frac{1}{1147}$
Tính giá trị biểu thức E = $\frac{1}{7}$ + $\frac{1}{91}$ +$\frac{1}{247}$ + $\frac{1}{415}$ + $\frac{1}{475}$ + … +$\frac{1}{1147}$
By Piper
@py
Bài làm :
`E = 1/7 +1/91 +1/247 + 1/475 + 1/775 + 1/1147`
`E = 1/(1.7) + 1 /(7.13) + 1/(13.19) + … + 1/(31.37)`
`E = 1/6 . 6/(1.7) + 1/6 . 6/(7.13) + … + 1/6 . 6/(31.27)`
`E = 1/6 . (1 – 1/7 + 1/7 – 1/13 + … + 1/31 – 1/37)`
`E = 1/6 . ( 1 – 1/ 37)`
`E = 1/6 . (36/37)`
`E = 6/37`
$E =$ `1/7` + `1/91` + `1/247` + `1/475` + `1/755` + `1/1147`
$E =$ `1/(1.7)` + `1/(7.13)` + `1/(13.19)` + `1/(19.25)` + `1/(25.31)` + `1/(31.37)`
$6E =$ `6/(1.7)` + `6/(7.13)` + `6/(13.19)` + `6/(19.25)` + `6/(25.31)` + `6/(31.37)`
$6E =$ 1 – `1/7` + `1/7` – `1/13` + `1/13` – `1/19` + `1/19` – `1/25` + `1/25` – `1/31` + `1/31` – `1/37`
$6E = 1$ – `1/37`
$6E =$ `36/37`
$E =$ `36/37` . `1/6`
$E =$ `6/37`
$Vậy E =$ `6/37`