=1/10+1/10+3/10+4/10+5/10+6/10+7/10+8/10+9/10

=1/10+45/10

=46/10=23/5

=2/10+3/10+4/10+......+13/10

=\(\frac{2+3+4+......+13}{10}\)

=90/10=9

k cho mình nha

=9 nhe cac ban

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

=1/10+2/10+3/10+4/10+5/10+6/10+7/10+8/10+9/10

=9/2

0,1  0,5    0,3du3    0,2 du8   0,2   0,1 du24  0,1du21  0,1 du16   0,1 du9

\(\frac{1}{5}+\frac{4}{10}+...+\frac{81}{45}=\frac{1}{5}+\frac{2}{5}+\frac{3}{5}+...+\frac{9}{5}=\frac{1+2+3+...+9}{5}=\frac{45}{5}=9\)

1/5 + 4/10 + 9/15 + 16/20 + 25/25 + 36/30 + 49/35 + 64/40 + 81/45

=1/5 + 2/5 + 3/5 + 4/5 + 5/5 + 6/5 + 7/5 + 8/5 + 9/5

=45/5 = 9

zvzxdcbgfd

1+2+3+4+5+6+7+8+9/10

\(\frac{41}{10}\)

#)Giải :

\(\frac{1}{15}+\frac{4}{30}+\frac{9}{45}+\frac{16}{60}+...+\frac{81}{135}=\frac{1}{15}+\frac{2}{15}+\frac{3}{15}+...+\frac{9}{15}=\frac{45}{15}=3\)

Dễ ẹc ak :v rút gọn là ra

=(\(\frac{1}{15}\)+\(\frac{4}{30}\)+\(\frac{16}{60}\)+\(\frac{64}{120}\))+(\(\frac{9}{45}\)+\(\frac{36}{90}\))+(\(\frac{25}{75}\)+\(\frac{81}{135}\))

=(\(\frac{8}{120}\)+\(\frac{16}{120}\)+\(\frac{32}{120}\)+\(\frac{64}{120}\))+(\(\frac{18}{90}\)+\(\frac{36}{90}\))+\(\frac{14}{15}\).

=1+\(\frac{3}{5}\)+\(\frac{14}{15}\).

=\(\frac{8}{5}\)+\(\frac{14}{15}\).

=\(\frac{15}{38}\)

Mình xin lỗi làm thiếu phân số cuối cùng

Bài đúng là thế này xin lỗi nhé. Kết quả chính xác là 4,5

\(=\frac{1}{10}+\frac{2.2}{2.10}+\frac{3.3}{3.10}+\frac{4.4}{4.10}+\frac{5.5}{5.10}+\frac{6.6}{6.10}+\frac{7.7}{7.10}+\frac{8.8}{8.10}+\frac{9.9}{9.10}=\)

\(=\frac{1}{10}+\frac{2}{10}+\frac{3}{10}+\frac{4}{10}+\frac{5}{10}+\frac{6}{10}+\frac{7}{10}+\frac{8}{10}+\frac{9}{10}=\)

\(=\frac{1+2+3+4+5+6+7+8+9}{10}=\frac{45}{10}=4,5\)

\(\frac{9}{2}\)= 4,5

\(=\frac{1}{10}+\frac{1}{5}+\frac{3}{10}+\frac{2}{5}+\frac{1}{2}+\frac{3}{5}+\frac{7}{10}+\frac{4}{5}+\frac{9}{10}=\left(\frac{1}{10}+\frac{3}{10}+\frac{7}{10}+\frac{9}{10}\right)+\left(\frac{1}{5}+\frac{2}{5}+\frac{3}{5}+\frac{4}{5}\right)+\frac{1}{2}\)

=2+2+1/2=4+1/2=9/2=4,5

a)     5/30+15/90+25/150+35/210+45/270

       =1/6+1/6+1/6+1/6+1/6

       =1/6 x 5

       =5/6

b)     1/2+1/6+1/12+1/20+....+1/56

        =1/1x2+1/2x3+1/3x4+1/4x5+.....1/7x8

        =1/1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+.......-1/7+1/7-1/8

        =1/1-1/8

         =7/8

c)     mình chịu

thank you bn nhìu nha

chịu,khó quá,nhất là câu c ý