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