\(\frac{8}{15}+\frac{16}{30}+\frac{3}{5}+\frac{9}{10}+2\frac{3}{5}\)

\(=\frac{8}{15}+\frac{16}{30}+\frac{3}{5}+\frac{9}{10}+\frac{13}{5}\)

\(=\frac{16+16+18+27+78}{30}\)

\(=\frac{155}{30}\)

\(=\frac{31}{6}\)

Hc tốt #

\(\frac{8}{15}\)+\(\frac{16}{30}\)+\(\frac{3}{5}\)+\(\frac{9}{10}\)+2\(\frac{3}{5}\)

=\(\frac{16}{30}\)+\(\frac{16}{30}\)+\(\frac{18}{30}\)+\(\frac{27}{30}\)+\(\frac{13}{5}\)

=\(\frac{16+16+18+27}{30}\)+\(\frac{78}{30}\)

=\(\frac{77}{30}\)+\(\frac{78}{30}\)= \(\frac{155}{30}\)

Ta có: \(1\frac{4}{5}+2\frac{5}{7}+3\frac{4}{5}+4\frac{5}{7}\)

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

\(=\left(\frac{9}{5}+\frac{19}{5}\right)+\left(\frac{19}{7}+\frac{33}{7}\right)\)

\(=\frac{28}{5}+\frac{52}{7}=13\frac{1}{35}\)

= ( \(1\frac{4}{5}\)+ \(3\frac{4}{5}\)) + (  \(2\frac{5}{7}\)+  \(4\frac{5}{7}\))         

=        \(4\frac{4}{5}\)           +       \(6\frac{5}{7}\)

=           \(\frac{24}{5}\)         +        \(\frac{47}{7}\)

=  ...... ( tính nốt nhé )

=(1+3)×4/5+(2+4)×5/7

=4×4/5+6×5/7

=16/5+30/7

=16×6/7

Kết quả là:

 5/10

  Đáp số: 5/10

\(\frac{3}{10}+\frac{7}{5}-\frac{2}{2}\)

\(=\frac{17}{10}-\frac{2}{2}\)

\(=\frac{7}{10}\)

\(\frac{3}{10}+\frac{7}{5}-\frac{2}{2}\)

\(=\frac{3}{10}+\frac{7}{5}-1\)

\(=\frac{17}{10}-1\)

\(=\frac{7}{10}\)

14/10 .15/19 -(4/5 + 2/3):2 +1/5

=7/5 .15/19 -(12/15 +10/15):11/5

=7/5.15/19 -22/15:11/5

=7/57-2/3

=7/57+(-38/57)

= -31/57

\(\frac{15}{49}\) mà

bt rùi hỏi làm j

Đặt \(A=\frac{1}{5}+\frac{1}{5^3}+...+\frac{1}{5^{101}}\)

\(\Rightarrow25A=5+\frac{1}{5}+\frac{1}{5^3}+...+\frac{1}{5^{99}}\)

\(\Rightarrow25A-A=\left(5+\frac{1}{5}+\frac{1}{5^3}+...+\frac{1}{5^{99}}\right)-\left(\frac{1}{5}+\frac{1}{5^3}+\frac{1}{5^5}+...+\frac{1}{5^{101}}\right)\)

hay \(24A=5-\frac{1}{5^{101}}\)

\(\Rightarrow A=\frac{5-\frac{1}{5^{101}}}{24}\)

\(\Rightarrow A:\left(1-\frac{1}{5^{102}}\right)=\frac{5-\frac{1}{5^{101}}}{24}.\frac{1}{1-\frac{1}{5^{102}}}\)

\(=\frac{5\left(1-\frac{1}{5^{102}}\right)}{24}.\frac{1}{1-\frac{1}{5^{102}}}=\frac{5}{24}\)

Ta có: \(A=\frac{1}{3}-\frac{3}{4}+\frac{3}{5}+\frac{1}{73}-\frac{1}{36}+\frac{1}{15}-\frac{2}{9}\)

\(A=\left(\frac{1}{3}-\frac{2}{9}\right)+\left(\frac{3}{5}+\frac{1}{15}\right)-\frac{3}{4}-\frac{1}{36}+\frac{1}{73}\)

\(A=\left(\frac{3}{9}-\frac{2}{9}\right)+\left(\frac{9}{15}+\frac{1}{15}\right)-\left(\frac{3}{4}+\frac{1}{36}\right)+\frac{1}{73}\)

\(A=\frac{1}{9}+\frac{10}{15}-\frac{7}{9}+\frac{1}{73}\)

\(A=\frac{1}{9}+\frac{2}{3}-\frac{7}{9}+\frac{1}{73}\)

\(A=\frac{1}{9}+\frac{6}{9}-\frac{7}{9}+\frac{1}{73}\)

\(A=\frac{7}{9}-\frac{7}{9}+\frac{1}{73}\)

\(A=\frac{1}{73}\)

Vậy: \(A=\frac{1}{73}\)

cho mik hỏi k kiểu j z

a. 5x +2 4/5 = 15

=> 5x + 14/5 = 15

=> 5x = 15 - 14/5 = 61/5

=> x = 61/5 : 5 

=> x = 61/25

a)5x + 2 4/5 =15

5x+14/5=15

5x=15- 14/5

5x=71/5

x=71/5 :5

x=71

X-105:3=-23

X-35=-23

x=-23+(-35)

x=-88

Ta có : 

\(\frac{\frac{2}{5}-\frac{2}{9}+\frac{2}{11}}{\frac{7}{5}-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)

\(=\)\(\frac{2\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}{7\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{11}\right)}-\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{2}\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{5}\right)}\)

\(=\)\(\frac{2}{7}-\frac{1}{\frac{7}{2}}\)

\(=\)\(\frac{2}{7}-\frac{2}{7}\)

\(=\)\(0\)

Chúc bạn học tốt ~ 

thank nha

k cho mk nhé .OK

\(\frac{-2}{5}.\left(\frac{5}{17}-\frac{9}{15}\right)-\frac{-2}{5}.\left(\frac{2}{17}+\frac{-2}{5}\right)\)

\(=\frac{-2}{5}.\frac{5}{17}-\frac{-2}{5}.\frac{3}{5}-\frac{-2}{5}.\frac{2}{17}-\frac{-2}{5}.\frac{-2}{5}\)

\(=\frac{-2}{5}.\left(\frac{5}{17}-\frac{2}{17}\right)-\frac{-2}{5}.\left(\frac{3}{5}+\frac{-2}{5}\right)\)

\(=\frac{-2}{5}.\frac{3}{17}-\frac{-2}{5}.\frac{1}{5}\)

\(=\frac{-2}{5}.\left(\frac{3}{17}-\frac{1}{5}\right)\)

\(=\frac{-2}{5}.\frac{-2}{85}\)

\(=\frac{4}{425}\)

\(\frac{-2}{5}.\left(\frac{5}{17}-\frac{9}{15}\right)-\frac{-2}{5}.\left(\frac{2}{17}+\frac{-2}{5}\right)\)

= \(\frac{-2}{5}.\frac{-26}{85}-\frac{-2}{5}.\frac{-24}{85}\)

= \(\frac{-2}{5}.\left(\frac{-26}{85}-\frac{-24}{85}\right)\)

= \(\frac{-2}{5}.\frac{-2}{85}\)

= \(\frac{4}{425}\)