Question

1+\(\frac{1}{3}\)+ \(\frac{1}{9}\)+ \(\frac{1}{27}\)+ \(\frac{1}{81}\)+ \(\frac{1}{243}\)+ \(\frac{1}{729}\)

Answer 1

=1093/729

ko bt có đung ko nữa

Answer 2

a=1 +1/3 +1/3^2 +1/3^3 +1/3^4 +1/3^5+1/3^6

3a=3 +1 +1/3 +1/3^2 + 1/3^3 +...+1/3^5

3a -a=[3 +1 +1/3 +1/3^2 +...+1/3^5] -1 -1/3 -1/3^2 -.........-1/3^6

2a =3- 1/3^6

a=[3-1/3^6] :2

Answer 3

\(1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+...+\frac{1}{729}\)

\(3A=3\left(1+\frac{1}{3}+\frac{1}{9}+....+\frac{1}{729}\right)\)

\(3A=3+\frac{1}{3}+\frac{1}{9}+....+\frac{1}{243}\)

\(3A-A=\left(3+\frac{1}{3}+\frac{1}{9}+...+\frac{1}{243}\right)-\left(1+\frac{1}{3}+...+\frac{1}{729}\right)\)

\(2A=3-\frac{1}{729}\)

\(2A=\frac{2187}{729}-\frac{1}{729}\)

\(2A=\frac{2186}{729}\)

\(A=\frac{1093}{729}\)