Câu trả lời hay nhất: Đặt A = 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
A x 3 = 3 x ﴾1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729﴿
= 1 + 1/3 + 1/9 + 1/27 + 1/81 + 1/243
A x 3 ‐ A = 1 + 1/3 + 1/9 + 1/27 + 1/81 + 1/243 ‐ ﴾1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729﴿
= 1 + 1/3 + 1/9 + 1/27 + 1/81 + 1/243 ‐ 1/3 ‐ 1/9 ‐ 1/27 ‐ 1/81 ‐ 1/243 ‐ 1/729
= 1 ‐ 1/729
A x 2 = 728/729
A = 364/729
NHỚ TK MK NHA
Tính nhanh : 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
tính nhanh
a) 1/2+1/4+1/8+1/16+1/32
b) 1/3+1/9+1/27+1/81+1/243+1/729
Tính nhanh:
1 + 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
Tính nhanh:
1+1/3+1/9+1/27+1/81+1/143+729=
giúp mình giải nhanh nha
Tính nhanh:
1+ 1/3 + 1/9 + 1/27 + 1/81 + 1/243 + 1/729
tính nhanh
1/3+1/9+1/27+1/81=1/243=1/729
Tính nhanh:
\(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\)
tính nhanh 1+3+9+27+81+243+729+2187+6561+19683+59049
\(A=1+\dfrac{1}{3}+\dfrac{1}{9}+\dfrac{1}{27}+\dfrac{1}{81}+\dfrac{1}{243}+\dfrac{1}{729}\)
Tính A
