M
math1996


Tính tổng sau:
a)[TEX]\frac{1}{1.3}+\frac{1}{3.5}+.........+\frac{1}{19.21}[/TEX]
b)[TEX](1-\frac{1}{2}).(1-\frac{1}{3}).(1-\frac{1}{4})..............(1-\frac{1}{100})[/TEX]
c)[TEX]\frac{\frac{3}{7}+\frac{-6}{13}+\frac{9}{25}}{\frac{6}{7}+\frac{-12}{13}+\frac{18}{25}}[/TEX]
ai làm đc mình thanks nhá


a)[TEX]\frac{1}{1.3}+\frac{1}{3.5}+.........+\frac{1}{19.21}[/TEX]
b)[TEX](1-\frac{1}{2}).(1-\frac{1}{3}).(1-\frac{1}{4})..............(1-\frac{1}{100})[/TEX]
c)[TEX]\frac{\frac{3}{7}+\frac{-6}{13}+\frac{9}{25}}{\frac{6}{7}+\frac{-12}{13}+\frac{18}{25}}[/TEX]
ai làm đc mình thanks nhá