Question

So sánh hai phân số 

\(A=\frac{10^9+5}{10^9-2}\) và \(B=\frac{10^9}{10^9-7}\)

Answer 1

 thấy B/A

 lớn hơn 1 .Vây  B

 lớn hơn A

Answer 2

\(A=\frac{10^9+5}{10^9-2}\)                                                                                                                                    
\(=\frac{10^9-2}{10^9-2}+\frac{7}{10^9-2}\)

\(=1+\frac{7}{10^9-2}\)

\(B=\frac{10^9}{10^9-7}\)

\(=\frac{10^9-7}{10^9-7}+\frac{7}{10^9-7}\)

\(=1+\frac{7}{10^9-7}\)

Vì \(7\over10^9-5\)<\(7\over10^9-7\) nên A<B