\(\frac{1}{9}\)+\(\frac{2}{9}\)+\(\frac{3}{9}\)+......\(\frac{7}{9}\)+\(\frac{8}{9}\)=?

\(\frac{111.......1}{n}\)=\(\frac{1}{9}\)x  \(\frac{999.....9}{n}\)= \(\frac{1}{9}\)x  (  10ⁿ - 1 )

bài 7:tính bằng cách thuận tiện nhất

a, 1/3+2/3...+3\(\frac{1}{3}\) + 3\(\frac{2}{3}\) =.......

b,9+9/2+9/4+9/8......+9/128+9/256=......

c,\(\frac{5}{3}\) +     \(\frac{5}{3\cdot5}\) +    \(\frac{5}{5\cdot7}\) + ......... +\(\frac{5}{101\cdot103}\) =.........

A=\(\frac{1}{2}\)x\(\frac{5}{7}\)+\(\frac{9}{7}\)x0,3+\(\frac{1}{2}\)x\(\frac{4}{7}\)+\(\frac{9}{4}\)+\(\frac{9}{7}\)x0.2

B=\(\frac{2002\cdot15-1}{2001+2002\cdot14}\)

Ai nhanh và đúng thì mình sẽ tick!!!!

A=\(\frac{1}{2}\)x\(\frac{5}{7}\)+\(\frac{9}{7}\)x0,3+\(\frac{1}{2}\)x\(\frac{4}{7}\)+\(\frac{9}{4}\)+\(\frac{9}{7}\)x0.2

B=\(\frac{2002\cdot15-1}{2001+2002\cdot14}\)

Ai nhanh và đúng thì mình sẽ tick!

Tính bằng cách hợp lý:

A=$$x\(\frac{5}{7}\)+\(\frac{9}{7}\)x0,3+\(\frac{1}{2}\)x\(\frac{4}{7}\)+\(\frac{9}{4}\)+\(\frac{9}{7}\)x0.2

B=\(\frac{2002\cdot15-1}{2001+2002\cdot14}\)

1 tinh

a 5/6 + 4/7 b 5/4 - 7/9 c 15/17 x 1/9 d 3/7 : 6/8

tính P biết :

   P= 1+ \(\frac{9}{45}\) + \(\frac{9}{105}\)+ \(\frac{9}{189}\)+ .....+\(\frac{9}{29997}\)

1+\(\frac{9}{45}\)+\(\frac{9}{105}\)+\(\frac{9}{189}\)+.......+\(\frac{9}{29997}\)

tính nhanh

\(a,\frac{11}{15}+\frac{5}{7}+\frac{2}{7}+\frac{4}{15}\)

\(b,\frac{5}{9}x\frac{1}{2}+\frac{5}{9}x\frac{6}{4}\)

\(c,\frac{7}{8}:\frac{1}{2}+\frac{9}{8}:\frac{1}{2}\)

\(d,\frac{17}{10}+\frac{1}{2}-\frac{7}{10}\)