a, `2/5 xx 3/7 +2/5 xx 4/7 = 2/5 xx (3/7+4/7)=2/5 xx 7/7 =2/5xx1=2/5`
b, `5/8xx5/4-5/8xx3/4=5/8xx(5/4-3/4)=5/8xx2/4=5/8xx1/2=5/16`
a, 2/5 x (3/7 + 4/7)
= 2/5 x 7/7
= 49/35
b, 5/8 x (5/4 - 3/4)
= 5/8 x 2/3
= 10
đó là kết quả đó!
a,\(\dfrac{2}{5}\) x \(\dfrac{3}{7}\) + \(\dfrac{2}{5}\) x \(\dfrac{4}{7}\) = \(\dfrac{6}{35}\) + \(\dfrac{8}{35}\) = \(\dfrac{14}{35}\) = \(\dfrac{2}{5}\)
b,\(\dfrac{5}{8}\) x \(\dfrac{5}{4}\) - \(\dfrac{5}{8}\) x \(\dfrac{3}{4}\) = \(\dfrac{25}{32}\) - \(\dfrac{15}{32}\) = \(\dfrac{10}{32}\) = \(\dfrac{5}{4}\)
