\(a,\frac{12345}{12342}=1+\frac{3}{12342}\)

    \(\frac{23457}{23455}=1+\frac{2}{23455}\)

Vì \(\frac{3}{12342}>\frac{2}{23455}\Rightarrow\frac{12345}{12342}>\frac{23457}{23455}\)

\(b,\frac{149}{150}=1-\frac{1}{150}\)

        \(\frac{4}{11}=1-\frac{7}{11}\)

Vì \(\frac{1}{150}< \frac{7}{11}\Rightarrow\frac{149}{150}>\frac{4}{11}\)

12345/12342 = 1 + 3/12342 = 1 + 1/ 4114 = 1 + 2/8228

23457/23455 = 1 + 2/23455

Có 1 + 2/8228 > 1 + 2/23455 => 12345/12342 > 23457/23455.

149/450 < 150/450 = 1/3

4/11 > 4/12 = 1/3

Vậy 149/450 < 4/11

Ta có : 3³⁹ < 3⁴⁰ = 9²⁰ < 11²⁰ <11²¹

Vậy 3³⁹ < 11²¹

kb voi mk nha

3/10 \(\le\)3/9   \(=\) 50/150   \(\le\)50/149

Ta có : \(\frac{1}{2.3}< \frac{1}{1.2}\)

            \(\frac{1}{3.4}< \frac{1}{2.3}\)

             \(\frac{1}{4.5}< \frac{1}{3.4}\)

               ...

              \(\frac{1}{99.100}< \frac{1}{98.99}\)

\(\Rightarrow A< \frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{98.99}\)

\(A< 1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{98}-\frac{1}{99}\)

\(A< 1-\frac{1}{99}< 1\)

\(\Rightarrow A< 1\)

A \(=\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{99.100}\)

     \(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{98}-\frac{1}{99}+\frac{1}{99}-\frac{1}{100}\)

       \(=\frac{1}{2}-\frac{1}{100}\)

         \(=\frac{49}{100}\)

         Vì \(\frac{49}{100}< 1\Rightarrow A< 1\)

          Chúc bn hk tốt :>

mẹt xi

hoi ngu vkl

4/5<1va 6/7     vay 2 phan so bang nhau

Qui đồng:

4/5 = (4 x 7)/(5 x 7) = 28/35

6/7 = (6 x 5)/(7 x 5) = 30/35

Do 28/35 < 30/35 nên 4/5 < 6/7

Tất cả là dzậy