a) \(\left(2+\dfrac{2}{3}-\dfrac{1}{2}\right)^2\cdot\left(1-\dfrac{1}{4}\right)\)
\(=\left(\dfrac{12}{6}+\dfrac{4}{6}-\dfrac{3}{6}\right)^2\cdot\left(\dfrac{4}{4}-\dfrac{1}{4}\right)\)
\(=\left(\dfrac{12+4-3}{6}\right)^2\cdot\dfrac{3}{4}\)
\(=\left(\dfrac{13}{6}\right)^2\cdot\dfrac{3}{4}\)
\(=\dfrac{169}{36}\cdot\dfrac{3}{4}\)
\(=\dfrac{169\cdot3}{36\cdot4}=\dfrac{169}{48}\)
b) \(12:\left(\dfrac{1}{3}-\dfrac{1}{6}\right)^2\)
\(=12:\left(\dfrac{2}{6}-\dfrac{1}{6}\right)^2\)
\(=12:\left(\dfrac{1}{6}\right)^2\)
\(=12:\dfrac{1}{36}\)
\(=432\)
\(\left(2+\dfrac{2}{3}-\dfrac{1}{2}\right)^2\cdot\left(1-\dfrac{1}{4}\right)\\ =\left(\dfrac{12}{6}+\dfrac{4}{6}-\dfrac{3}{6}\right)^2\cdot\left(\dfrac{4}{4}-\dfrac{1}{4}\right)\\ =\left(\dfrac{13}{6}\right)^2\cdot\dfrac{3}{4}\\ =\dfrac{169}{36}\cdot\dfrac{3}{4}\\ =\dfrac{507}{144}\\ =\dfrac{169}{48}\)
\(12:\left(\dfrac{1}{3}-\dfrac{1}{6}\right)^2\\ =12:\left(\dfrac{2}{6}-\dfrac{1}{6}\right)^2\\ =12:\left(\dfrac{1}{6}\right)^2\\ =12:\dfrac{1}{36}\\ =12\cdot36\\ =432\)
a: =(12/6+4/6-3/6)^2*3/4
=3/4*(13/6)^2=3/4*169/36=169/48
b: =12:(1/6)^2=12:1/36=432
