Bt1:Tìm x thuộc Z biết:
a,\(\dfrac{1}{3}\) + \(\dfrac{-2}{5}\) + \(\dfrac{1}{6}\) + \(\dfrac{-1}{5}\) ≤ x < \(\dfrac{-3}{4}\) + \(\dfrac{2}{7}\) + \(\dfrac{-1}{4}\) + \(\dfrac{3}{5}\) + \(\dfrac{5}{7}\)
Bt2:Tìm a,b ϵ N biết: \(\dfrac{a}{5}\) - \(\dfrac{2}{b}\) =\(\dfrac{2}{15}\)
Ta có: 1/3 + −2/5+ 1/6 + −1/5 ≤ x < −3/4+2/7+-1/4+3/5+5/7
⇒10-12+5-6/30≤ x< -105+40-35+84+100/140
⇒-3/30≤ x <84/140
⇒-0,1≤ x < 0,6
⇒x=0