sao lại có dấu x to đùng thế kia
\(\left[1+2\dfrac{1}{3}-3\dfrac{1}{4}\right]:\left[1+3\dfrac{7}{12}-4\dfrac{1}{2}\right]\)
\(=\left[3\dfrac{1}{3}-3\dfrac{1}{4}\right]:\left[4\dfrac{7}{12}-4\dfrac{1}{2}\right]\)
\(=\left[3\dfrac{4}{12}-3\dfrac{3}{12}\right]:\left[4\dfrac{7}{12}-4\dfrac{6}{12}\right]\)
\(=\dfrac{1}{12}:\dfrac{1}{12}\)
\(=1\)
Ta có: \(\left(1+2\dfrac{1}{3}-3\dfrac{1}{4}\right):\left(1+3\dfrac{7}{12}-4\dfrac{1}{2}\right)\)
\(=\left(1+\dfrac{7}{3}-\dfrac{13}{4}\right):\left(1+\dfrac{43}{12}-\dfrac{9}{2}\right)\)
\(=\left(\dfrac{12}{12}+\dfrac{28}{12}-\dfrac{39}{12}\right):\left(\dfrac{12}{12}+\dfrac{43}{12}-\dfrac{54}{12}\right)\)
\(=\dfrac{1}{12}:\dfrac{1}{12}\)
=1
dấu x làm hình cho đẹp