Question

Tính giá trị biểu thức :

( \(\dfrac{1}{2}\) - 2 + \(\dfrac{2}{3}\) ) - ( 7 + \(\dfrac{1}{2}\) - \(\dfrac{2}{3}\) ) - ( \(\dfrac{1}{2}\) - \(\dfrac{2}{3}\) - 5 )

Bằng 2 cách .

Answer 1

\(\left(\dfrac{1}{2}-2+\dfrac{2}{3}\right)-\left(7+\dfrac{1}{2}-\dfrac{2}{3}\right)-\left(\dfrac{1}{2}-\dfrac{2}{3}-5\right)\)

\(=\dfrac{1}{2}-2+\dfrac{2}{3}-7-\dfrac{1}{2}+\dfrac{2}{3}-\dfrac{1}{2}+\dfrac{2}{3}+5\)

\(=\left(\dfrac{1}{2}-\dfrac{1}{2}-\dfrac{1}{2}\right)+\left(\dfrac{2}{3}+\dfrac{2}{3}+\dfrac{2}{3}\right)-\left(2+7-5\right)\)

\(=-\dfrac{1}{2}+2-4\)

\(=-\dfrac{1}{2}-2\)

\(=-\dfrac{1}{2}-\dfrac{4}{2}\)

\(=-\dfrac{5}{2}\)