Tính:
a) \(\displaystyle{{5 \times 6 \times 7 \times 8} \over {6 \times 7 \times 8 \times 9}}\)
b) \(\displaystyle{{42 \times 32} \over {12 \times 14 \times 16}}\)
a) \(\displaystyle {{5 \times 6 \times 7\times 8} \over {6 \times 7 \times 8 \times 9}} = \dfrac{5 \times \not{6}\times \not{7}\times \not{8}} {\not{6}\times \not{7} \times \not{8} \times 9}=\dfrac{5}{9}\)
b) \(\displaystyle {{42 \times 32 } \over {12 \times 14 \times 16}} = \dfrac{\not{14}\times 3 \times\not{16}\times 2} {12\times \not{14} \times \not{16}}=\dfrac{6}{12} = \dfrac{1}{2}\)
-- Mod Toán lớp 4