\(\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\)
\(=\frac{243}{729}+\frac{81}{729}+\frac{27}{729}+\frac{9}{729}+\frac{3}{729}+\frac{1}{729}\)
\(=\frac{4}{9}+\frac{27}{729}+\frac{9}{729}+\frac{3}{729}+\frac{1}{729}\)
\(=\frac{13}{27}+\frac{9}{729}+\frac{3}{729}+\frac{1}{729}\)
\(=\frac{40}{81}+\frac{3}{729}+\frac{1}{729}\)
\(=\frac{121}{243}+\frac{1}{729}\)
\(=\frac{364}{729}\).
Ủng hộ nha !
A= 1/3+1/9+1/27+1/81+1/243+1/729
A= (1-1/3)+(1/3-1/9)+(1/9-1/27)+(1/27-1/81)+(1/81-1/243)+(1/243-1/729)
A= 1-1/3+1/3-1/9+1/9-1/27+1/27-1/81+1/81-1/243+1/243-1/729
Triệt tiêu từ 1/3 đến 1/243
A= 1-1/729
A = 729/729 - 1/729= 91
Đ/S 9 mình nha
Quy đồng mẫu số : MSC=729
1/3+1/9+1/27+1/81+1/243+1/729
= 243/729+81/729+27/729+9/729+3/729+1/729
= 364/729
ĐÁP SỐ : 364/729 ::::::))))))
1/3+1/9+1/27+1/81+1/243+1/729
= 243+81+27+9+3+1/729
= (243+27)+(81+9)+(3+1)/729
= 270+90+4/729
= 364/729
