So sánh giá trị của biểu thức \(A=\dfrac{(-1)^2}{5}+\Big(1-\dfrac{3}{2}\Big)^2.1\dfrac{1}{3}-\dfrac{5}{6}\) với \(0\).
\(A>0.\)\(A< 0.\)\(A\geq0.\)\(A=0.\)Hướng dẫn giải:\(A=\dfrac{(-1)^2}{5}+\Big(1-\dfrac{3}{2}\Big)^2.1\dfrac{1}{3}-\dfrac{5}{6}\)
\(=\dfrac{1}{5}+\Big(\dfrac{-1}{2}\Big)^2.\dfrac{4}{3}-\dfrac{5}{6}\)
\(=\dfrac{1}{5}+\dfrac{1}{4}.\dfrac{4}{3}-\dfrac{5}{6}\)
\(=\dfrac{1}{5}+\dfrac{1}{3}-\dfrac{5}{6}\)
\(=\dfrac{8}{15}-\dfrac{5}{6}\)
\(=\dfrac{-3}{10}\)
Vậy \(A<0.\)
