\(A=\frac{5+55+555+5555}{9+99+999+9999}=\frac{5.\left(1+11+111+1111\right)}{9.\left(1+11+111+1111\right)}=\frac{5}{9}\)

Tớ làm luôn

A=\(\frac{5.\left(1+11+111+1111\right)}{9.\left(1+11+111+1111\right)}\)

A=\(\frac{5}{9}\)

\(A=\frac{\left(5.1+5.11+5.111+5.1111\right)}{9.1+9.11+9.111+9.1111}\)

\(A=\frac{5.\left(1+11+111+1111\right)}{9.\left(1+11+111+1111\right)}\)

\(\Rightarrow A=\frac{5}{9}\)

Chúc em học tốt^^

\(\frac{5+55+555+5555}{9+99+999+9999}=\)

\(=\frac{5x\left(1+11+111+1111\right)}{9x\left(1+11+111+1111\right)}=\frac{5}{9}\)

\(\frac{5+55+555+5555}{9+99+999+9999}=\frac{5.\left(1+11+111+1111\right)}{9.\left(1+11+111+1111\right)}=\frac{5}{9}\)\(\frac{5}{9}\)

dấu chấm bạn cứ hiểu là nhân nhé !

\(\frac{5+55+555+5555}{9+99+999+9999}=\frac{5+11x5+111x5+1111x5}{9+11x9+111x9+1111x9}\)\(=\frac{5x5x5x5}{9x9x9x9}=\frac{625}{6561}\)

A = \(\frac{6170}{11106}=\frac{5}{9}\)

\(A=\frac{8\cdot4\cdot125\cdot25+96524+2476}{10\cdot125\cdot4\cdot25\cdot8}\)

\(A=\frac{1+96524+2476}{10}\)

\(A=\frac{99001}{10}\)

\(B=\frac{5+55+555+5555}{9+99+999+9999}\)

\(B=\frac{9}{5}\)

1 ở đâu ra vậy bạn

a, \(\dfrac{3.5.7.11.13.37-10101.55}{1212120+40404}\)

\(=\dfrac{55\left(3.7.13.37-10101\right)}{1212120+40404}\)

\(=\dfrac{55.0}{1212120+40404}=0\)

b, \(\dfrac{5+55+555+5555}{9+99+999+9999}\)

\(=\dfrac{5.\left(1+11+111+1111\right)}{9.\left(1+11+111+1111\right)}=\dfrac{5}{9}\)

Chúc bạn học tốt!!!

a,\(\dfrac{3.5.7.11.13.37-10101.55}{1212120+40404}\)

\(=\dfrac{55\left(3.7.13.37-10101\right)}{1212120+40404}\)

\(=\dfrac{55.0}{1212120+40404}=0\)

\(\frac{5+55+555+5555}{9+99+999+9999}=\frac{5\cdot\left(1+11+111+1111\right)}{9\cdot\left(1+11+111+1111\right)}=\frac{5}{9}\)

    \(\frac{5+55+555+5555}{9+99+999+9999}\)

= \(\frac{5.\left(1+11+111+1111\right)}{9.\left(1+11+111+1111\right)}\)

= \(\frac{5}{9}\)

\(3A=9+99+....+99....99=10-1+10^2-1+...+10^{50}-1\)

\(=\left(10+10^2+...+10^{50}\right)-50\)

Đến đây dễ hơn rồi.

\(\frac{9}{5}B=9+99+...+99.99\)tương tự A

C tương tự A.

tự làm

ngu si thì không biết làm

=5phần9