Question

Câu 2.Thực hiện phép tính:

a) \(\left(\dfrac{-1}{7}\right)^0-2\dfrac{4}{9}.\left(\dfrac{2}{3}\right)^2\)

b)\(\left(\dfrac{1}{3}-\dfrac{5}{6}\right)^2+\dfrac{5}{6}:2\)

Answer 1

a) \(\left(-\dfrac{1}{7}\right)^0-2\dfrac{4}{9}.\left(\dfrac{2}{3}\right)^2\)

\(=1-\dfrac{22}{9}.\dfrac{4}{9}\)

\(=1-\dfrac{88}{81}\)

\(=\dfrac{81}{81}-\dfrac{88}{81}\)

\(=\dfrac{-7}{81}\)

b) \(\left(\dfrac{1}{3}-\dfrac{5}{6}\right)^2+\dfrac{5}{6}:2\)

\(=\left(\dfrac{2}{6}-\dfrac{5}{6}\right)^2+\dfrac{5}{6}.\dfrac{1}{2}\)

\(=\left(\dfrac{-1}{2}\right)^2+\dfrac{5}{12}\)

\(=\dfrac{1}{4}+\dfrac{5}{12}\)

\(=\dfrac{3}{12}+\dfrac{5}{12}\)

\(=\dfrac{8}{12}=\dfrac{2}{3}\)

Answer 2

a) \(\left(-\dfrac{1}{7}\right)^0-2\dfrac{4}{9}.\left(\dfrac{2}{3}\right)^2\)
\(=0-\dfrac{22}{9}.\dfrac{4}{9}\)
\(=0-\dfrac{88}{81}\)
\(=-\dfrac{88}{81}\)
b) \(\left(\dfrac{1}{3}-\dfrac{5}{6}\right)^2+\dfrac{5}{6}:2\)
\(=\left(\dfrac{2}{6}-\dfrac{5}{6}\right)^2+\dfrac{5}{6}.\dfrac{1}{2}\)
\(=\left(-\dfrac{3}{6}\right)^2+\dfrac{5}{12}\)
\(=\left(-\dfrac{1}{2}\right)^2+\dfrac{5}{12}\)
\(=\dfrac{1}{4}+\dfrac{5}{12}\)
\(=\dfrac{3}{12}+\dfrac{5}{12}\)
\(=\dfrac{8}{12}\)
\(=\dfrac{2}{3}\)