Question

Answer 1

Bài 4: 

\(S=1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{16}=1-\dfrac{1}{16}=\dfrac{15}{16}\)

Bài 6: 

a: \(\Leftrightarrow x-\dfrac{1}{2}=\dfrac{1}{4}\)

hay x=3/8

b: \(\Leftrightarrow\dfrac{x}{5}=\dfrac{-1}{2}\)

hay x=-5/2

c: \(\Leftrightarrow x+\dfrac{2}{3}=\dfrac{1}{9}\)

hay x=-5/9