Question

Tính:

A= \(\frac{1}{2.9}\)+ \(\frac{1}{9.7}\)+\(\frac{1}{7.19}\)+...+\(\frac{1}{252.509}\)

B= \(\frac{1}{10.9}\)+\(\frac{1}{18.13}\)+\(\frac{1}{26.17}\)+...+\(\frac{1}{802.405}\)

C= \(\frac{2}{4.7}\)- \(\frac{3}{5.9}\)+\(\frac{2}{7.10}\)- \(\frac{3}{9.13}\)+...+\(\frac{2}{301.304}\)- \(\frac{3}{401.405}\)

Answer 1

28373822839999999999999399393393933939939393393939393939393939933939393939393939393993939393939399393

Answer 2

C= 24.7 - 35.9 +27.10 - 39.13 +...+2301.304 - 

Answer 3

564564654546544444444444444444444444444444456456

Answer 4

\(A=\frac{1}{2\cdot9}+\frac{1}{9\cdot7}+\frac{1}{7\cdot19}+...+\frac{1}{252.509}\)

\(2A=\frac{2}{2\cdot9}+\frac{2}{9\cdot7}+\frac{2}{7\cdot19}+...+\frac{2}{252\cdot509}\)

2A\(=\frac{1}{2}-\frac{1}{9}+\frac{1}{9}-\frac{1}{7}+\frac{1}{7}-\frac{1}{19}+...+\frac{1}{252}-\frac{1}{509}\)

2A \(=\frac{1}{2}-\frac{1}{509}\)

2A \(=\frac{507}{1018}\)=> A\(=\frac{507}{1018}:2=\frac{507}{2036}\)

MK LÀM KO BIẾT CÓ ĐÚNG KO. CHÚC BẠN HỌC TỐT =~=

Answer 5

\(\Rightarrow\frac{5}{2}A=\frac{5}{4.9}+\frac{5}{9.14}+\frac{5}{14.19}+...+\frac{5}{504.509}\)

\(\Rightarrow\frac{5}{2}A=\frac{1}{4}-\frac{1}{9}+\frac{1}{9}-\frac{1}{14}+...+\frac{1}{504}-\frac{1}{509}\)

\(\Rightarrow\frac{5}{2}A=\frac{1}{4}-\frac{1}{509}\Rightarrow A=\frac{\frac{1}{4}-\frac{1}{509}}{\frac{5}{2}}\)