Question

 

Mik đang cần Đ/A bài này gấp các bn giúp mik vs ạ

Answer 1

(Đề) 

`A = -1/(4.5) - 1/(5.6) - ... - 1/(11.12) `

`A = - (1/(4.5) +1/(5.6) + ... + 1/(11.12) )`

`A = - (1/4 - 1/5 + 1/5 - 1/6 +... + 1/11 - 1/12)`

`A = - (1/4 - 1/12)`

`A = - 1/6`

Answer 2

Answer 3

\(A=-\left(\dfrac{1}{4.5}+\dfrac{1}{5.6}+...+\dfrac{1}{11.12}\right)\)

\(=-\left(\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+...+\dfrac{1}{11}-\dfrac{1}{12}\right)\)

\(=-\left(\dfrac{1}{4}-\dfrac{1}{12}\right)\)

\(=-\dfrac{1}{6}\)