Question

Answer 1

bài 1
a)
\(\dfrac{-5}{9}+\dfrac{8}{15}-\dfrac{2}{11}+\dfrac{4}{-9}+\dfrac{7}{15}\)
=\(\left(\dfrac{-5}{9}+\dfrac{-4}{9}\right)+\left(\dfrac{8}{15}+\dfrac{7}{15}\right)-\dfrac{2}{11}\)
=-1+1-\(\dfrac{2}{11}\)
= -\(\dfrac{2}{11}\)
b)
\(\dfrac{-7}{19}.\dfrac{8}{11}+\dfrac{3}{11}.\dfrac{-7}{19}+\dfrac{-12}{19}\)
\(=\dfrac{-7}{19}\left(\dfrac{8}{11}+\dfrac{3}{11}\right)+\dfrac{-12}{19}\)
= \(\dfrac{-7}{19}+\dfrac{-12}{19}\)
=-1
 

Answer 2

Bài 3:

a: Để B là số nguyên thì \(x-2⋮x+3\)

\(\Leftrightarrow x+3\in\left\{1;-1;5;-5\right\}\)

hay \(x\in\left\{-2;-4;2;-8\right\}\)