Ta có: a<b, c<d =>a+c<b+d.

a+c<b+d

vì a với c nhỏ hơn hơn b với d

nên a + c<b+d

a)

\(\frac{13}{27}=\frac{13.101}{27.101}=\frac{1313}{2727}\)

=> \(\frac{13}{27}=\frac{1313}{2727}\)

b)

\(-\frac{15}{23}=-\frac{15.10101}{23.10101}=-\frac{151515}{232323}\)

=>\(-\frac{15}{23}=-\frac{151515}{232323}\)

a) \(\frac{1313}{2727}=\frac{1313:101}{2727:101}=\frac{13}{27}\)

Vậy \(\frac{13}{27}=\frac{1313}{2727}\)

b) \(-\frac{151515}{232323}=\frac{-151515:10101}{232323:10101}=-\frac{15}{23}\)

Vậy \(-\frac{15}{23}=-\frac{151515}{232323}\)

\(A=\frac{19^{30}+5}{19^{31}+5}=>19A=\frac{19^{31}+95}{19^{31}+5}=1+\frac{90}{19^{31}+5}\left(1\right)\)

\(B=\frac{19^{31}+5}{19^{32}+5}=>19B=\frac{19^{32}+95}{19^{32}+5}=1+\frac{90}{19^{32}+5}\left(2\right)\)

từ (1) and (2)

=>19A>19B

=>A>B

ta có : (1/8)⁵=(1/2³)⁵

               =1/2¹⁵

vì 1/2¹⁵=1/2¹⁵ => 1/2¹⁵=1/8⁵

CẢM ƠN NHIỀU NHA ^^

Có 2^285 = (2^3)^95 = 8^95

     3^190 = (3^2)^95 = 9^95

Vì 8^95 < 9^95 nên 2^285 < 3^190

2²⁸⁵> 3¹⁹⁰

So sánh :

\(2^{285}\)và \(3^{190}\)

\(\Rightarrow2^{285}>3^{190}\)

27/31<2727/3131

11/31<111/311

Bài 1

a) \(7\times\dfrac{3}{14}-\dfrac{1}{14}=\dfrac{21}{14}-\dfrac{1}{14}=\dfrac{20}{14}=\dfrac{10}{7}\)

b) \(\dfrac{3}{2}+\dfrac{7}{4}\times\dfrac{2}{5}=\dfrac{3}{2}+\dfrac{14}{20}=\dfrac{11}{5}\)

c) \(\dfrac{9}{8}\div3+\dfrac{7}{8}\div3=\dfrac{9}{8}\times\dfrac{1}{3}+\dfrac{7}{8}\times\dfrac{1}{3}=\dfrac{9}{24}+\dfrac{7}{24}=\dfrac{16}{24}=\dfrac{2}{3}\)

d) \(2\div\dfrac{3}{4}-\dfrac{5}{8}\times\dfrac{4}{3}=\dfrac{8}{3}-\dfrac{20}{24}=\dfrac{64}{24}-\dfrac{20}{24}=\dfrac{11}{6}\)

a)7x3/14-1-1/14=21/14-1/14=20/14=10/7

b)3/2+7/4x2/5=3/2+14/20=60/20+14/20=74/20=37/10

c)9/8:3+7/8:3=9/24+7/24=16/24=2/3

d) 

A>B

mk nhắc rồi na

Anh qua câu hỏi của em đi, có ng trả lời mà, sao em hỏi nảy h anh ko trả lời

\(A=1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{15}+\frac{1}{16}\)

 \(=1+\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}\right)+\left(\frac{1}{6}+\frac{1}{7}+\frac{1}{8}\right)+\left(\frac{1}{9}+\frac{1}{10}+\frac{1}{11}\right)+\left(\frac{1}{12}+\frac{1}{13}+\frac{1}{14}\right)\)

\(+\left(\frac{1}{15}+\frac{1}{16}\right)\)

Vì \(\frac{1}{6}+\frac{1}{7}+\frac{1}{8}< 3\times\frac{1}{6}=\frac{1}{2}\)

\(\frac{1}{9}+\frac{1}{10}+\frac{1}{11}< 3\times\frac{1}{9}=\frac{1}{3}\)

\(\frac{1}{12}+\frac{1}{13}+\frac{1}{14}< 3\times\frac{1}{12}=\frac{1}{4}\)

\(\frac{1}{15}+\frac{1}{16}< 3\times\frac{1}{15}=\frac{1}{5}\)

\(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}< 3\times\frac{1}{2}=\frac{3}{2}\)

\(\Rightarrow A=1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{15}+\frac{1}{16}< 1+\frac{3}{2}+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}\)

\(\frac{1}{6}+\frac{1}{7}+\frac{1}{8}+...+\frac{1}{15}+\frac{1}{16}< \frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}\)

P.s Mình tịt rồi , bạn cố gắng giải ra nhá ^.^!!