a)\(\frac{7\cdot15:25\cdot102}{7\cdot4\cdot15\cdot3:25\cdot4\cdot102\cdot3}=\frac{1}{4\cdot3:4\cdot3}=\frac{1}{1}=1\)

b)\(\frac{2}{10}+\frac{3}{10}+\frac{4}{10}+\frac{5}{10}+\frac{6}{10}+\frac{7}{10}+\frac{8}{10}=\frac{2+3+4+5+6+7+8}{10}=\frac{44}{10}=\frac{22}{5}\)

\(\frac{2}{6}+\frac{4}{14}+\frac{22}{12}+16+\frac{2}{9}\)

\(=\frac{1}{3}+\frac{2}{7}+\frac{11}{6}+16+\frac{2}{9}\)

\(=\frac{42}{126}+\frac{36}{126}+\frac{231}{126}+\frac{28}{126}+16\)

\(=\frac{337}{126}+16\)

\(=18\frac{85}{126}\)

chúc bạn học tốt

Đ/S = \(18\frac{85}{126}\)

Chúc bạn hk tốt!! >> NGUYỄN DIỆU HẰNG<<  

9/1-1/90-1/72-1/56-1/42-1/30-1/20-1/12-1/6-1/2=0/4

Giải :

ta có

  \(\frac{9}{10}-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{90}\right)\)

=\(\frac{9}{10}-\left(\frac{1}{1\times2}+\frac{1}{2\times3}+...+\frac{1}{9\times10}\right)\)

=\(\frac{9}{10}-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{9}-\frac{1}{10}\right)\)

=\(\frac{9}{10}-\left[1+\left(\frac{-1}{2}+\frac{1}{2}\right)+\left(\frac{-1}{3}+\frac{1}{3}\right)+...+\left(\frac{-1}{9}+\frac{1}{9}\right)-\frac{1}{10}\right]\)

=\(\frac{9}{10}-\left(1-\frac{1}{10}\right)\)

=\(\frac{9}{10}-1+\frac{1}{10}=0\)                  (Mong online math ks cho mình nhé)

Sao mà mình hỏi bài này từ lâu lắm rồi mà vẫn chưa có bạn nào trả lời nhỉ?

     A)   \(\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}+\dfrac{1}{64}\)

2A= \(1+\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}\)

2A-A = \(1-\dfrac{1}{32}\)

A=  \(\dfrac{31}{32}\)

6/5 > 5/6

8/9 > 21/81

9/63 < 90/7

8/81 < 10/9

Tk mk nha

so sánh với 1

rút gọn hoặc quy đồng số còn lại để so sánh tử

so sánh với 1

cũng so sánh với 1

bạn đùa hay hỏi thật vậy

a)\(\dfrac{5}{7}+\dfrac{4}{9}=\dfrac{45}{63}+\dfrac{28}{63}=\dfrac{73}{63}\) ; \(\dfrac{9}{11}+\dfrac{3}{8}=\dfrac{72}{88}+\dfrac{33}{88}=\dfrac{105}{88}\)

\(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\); \(\dfrac{16}{25}-\dfrac{2}{5}=\dfrac{16}{25}-\dfrac{10}{25}=\dfrac{6}{25}\)

b)\(5+\dfrac{3}{5}=\dfrac{25}{5}+\dfrac{3}{5}=\dfrac{28}{5};10-\dfrac{9}{16}=\dfrac{160}{16}-\dfrac{9}{16}=\dfrac{151}{16}\)

\(\dfrac{2}{3}-\left(\dfrac{1}{6}+\dfrac{1}{8}\right)=\dfrac{2}{3}-\left(\dfrac{8}{48}+\dfrac{6}{48}\right)=\dfrac{2}{3}-\dfrac{14}{48}=\dfrac{32}{48}-\dfrac{14}{48}=\dfrac{3}{8}\)

\(\frac{9}{8}>\frac{8}{9}\)

\(\frac{16}{23}>\frac{16}{25}\)

\(\frac{8}{11}< \frac{8}{10}\)

\(\frac{10}{13}>\frac{19}{26}\)

\(\frac{13}{15}< \frac{11}{10}\)

\(\frac{11}{9}=\frac{44}{36}\)

9/8 > 8/9 

16/23 > 16/25 

8/11 < 8/10 

10/13 > 19/26 

13/15 < 11/10 

11/9 = 44/36 

Tham khảo nha !

Chúc bạn học giỏi !

=3/10+13/10

=16/10

\(=\frac{8}{5}=1\frac{3}{5}\)

k mình nha