Question

tính bằng cách thuận tiện

3/4 + 2/5 nhân 1/4 + 2/5 

Answer 1

3/4 + 2/5 x 1/4 + 2/5 

2/5 x ( 3/4 + 1/4)

=2/5 x 1

=2/5

Answer 2

\(\dfrac{3}{4}+\dfrac{2}{5}\times\dfrac{1}{4}+\dfrac{2}{5}=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)\times\dfrac{2}{5}=\dfrac{4}{4}\times\dfrac{2}{5}=1\times\dfrac{2}{5}=\dfrac{2}{5}\)

Answer 3