Question

Cho dãy vô hạn tuần hoàn sau:x=0,818181...

Y=1,222222...

Tính tích của x nhân y

 

Answer 1

Ta có:

\(x=0,818181...=0,\left(81\right)=\frac{81}{99}=\frac{9}{11}\)

\(y=1,222222...=1,\left(2\right)=1+0,\left(2\right)=1+\frac{2}{9}=\frac{11}{9}\)

\(\Rightarrow x.y=\frac{9}{11}.\frac{11}{9}=1\)

Vậy x.y = 1

Answer 2

Ta có :

\(x=0,\left(81\right)=\frac{81}{99}=\frac{9}{11}\)

\(y=1,\left(2\right)=1+\frac{2}{9}=\frac{11}{9}\)

\(\Rightarrow x=\frac{1}{y}\Rightarrow xy=1\)

Vậy ...

Answer 3

\(x=0,818181=0,\left(81\right)=\frac{9}{11}\)

\(y=1,222222=1,\left(2\right)=\frac{11}{99}\)

\(\Rightarrow x.y=\frac{9}{11}.\frac{11}{9}=1\)