Giải bài 4 trang 123 - SGK Toán lớp 4
Tính:
a) \(\dfrac{2\,\times\,3\,\times\,4\,\times\,5}{3\,\times\,4\,\times\,5\,\times\,6};\) b) \(\dfrac{9\,\times\,8\,\times\,5}{6\,\times\,4\,\times\,15}.\)
a) \(\dfrac{2\,\times\,3\,\times\,4\,\times\,5}{3\,\times\,4\,\times\,5\,\times\,6}=\dfrac {\cancel{2} \times \cancel{3} \times \cancel{4} \times \cancel{5}} {\cancel{3} \times \cancel{4} \times \cancel{5} \times \cancel{6}}=\dfrac{1}{3} \)
b) \(\dfrac{9\,\times\,8\,\times\,5}{6\,\times\,4\,\times\,15}=\dfrac{3\,\times\,3\,\times\,4\,\times\,2\,\times\,5}{3\,\times\,2\,\times\,4\,\times\,5\,\times\,3}=\dfrac {\cancel{3} \times \cancel{3} \times \cancel{4} \times \cancel{2}\times \cancel{5}} {\cancel{3} \times \cancel{2}\times \cancel{4}\times \cancel{5}\times \cancel{3}}=1 \)
