a)
\(\dfrac{1}{12}+\dfrac{1}{8}-\dfrac{1}{4}\)
\(=\dfrac{8}{96}+\dfrac{12}{96}-\dfrac{1}{4}\)
\(=\dfrac{5}{24}-\dfrac{1}{4}\)
\(=\dfrac{5}{24}-\dfrac{6}{24}\)
\(=\dfrac{-1}{24}\)
b)
\(\dfrac{-3}{4}.\dfrac{1}{3}-\dfrac{1}{7}\)
\(=\dfrac{-1}{4}-\dfrac{1}{7}\)
\(=\dfrac{-7}{28}-\dfrac{4}{28}\)
\(=\dfrac{-11}{28}\)
c)
\(\dfrac{2}{9}-\dfrac{1}{15}-\dfrac{14}{15}\)
\(=\dfrac{2}{9}-\left(\dfrac{1}{15}-\dfrac{14}{15}\right)\)
\(=\dfrac{2}{9}-\dfrac{-13}{15}\)
\(=\dfrac{30}{135}-\dfrac{-177}{135}\)
\(=\dfrac{23}{15}\)
a: \(=\dfrac{2}{24}+\dfrac{3}{24}-\dfrac{6}{24}=\dfrac{-1}{24}\)
b: \(=\dfrac{-1}{4}-\dfrac{1}{7}=-\dfrac{11}{28}\)
c: \(=\dfrac{2}{9}-1=-\dfrac{7}{9}\)
