Question

giúp em với ạ,em cần gấp!!!!!!!

Answer 1

\(\Leftrightarrow1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{8}{9}\)

\(\Leftrightarrow1-\dfrac{1}{x+1}=\dfrac{8}{9}\)

\(\Leftrightarrow\dfrac{1}{x+1}=\dfrac{1}{9}\)

=>x+1=9

hay x=8

Answer 2

\(\Leftrightarrow\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{8}{9}\)

\(\Leftrightarrow1-\dfrac{1}{x+1}=\dfrac{8}{9}\)

\(\Leftrightarrow-\dfrac{1}{x+1}=\dfrac{8}{9}-1\)

\(\Leftrightarrow-\dfrac{1}{x+1}=-\dfrac{1}{9}\)

\(\Leftrightarrow x+1=9\)

\(\Leftrightarrow x=8\)

 

Answer 3

−1x+1=−19⇔👉👉−1x+1=−19

$👉x+1=9$

$👉x=8$