Question

Tính bằng 2 cách:

(2/3 x 4/5) x 5/6

(1/2 + 1/3) x 1/5

(2/3 x 4/5) x 5/6

(1x2 + 1/3) x 1/5

Answer 1

(2/3 x 4/5) x 5/6

=   8/15     x 5/6

=             4/9

(2/3 x 4/5) x 5/6 

= (5/6 x 4/5) x 2/3

=        2/3     x 2/3

=              4/9

(1/2 + 1/3) x 1/5

=   5/6        x 1/5

=               1/6

(1/2 + 1/3) x 1/5

= (1/2 x 1/5) + (1/3 x 1/5)

=       1/10    +        1/15

=                 1/6

4A6?

Answer 2

Đây bạn nhé

Answer 3

cách1\(\left(\frac{2}{3}\times\frac{4}{5}\right)\times\frac{5}{6}\)=\(\frac{8}{15}\times\frac{5}{6}\)=\(\frac{4}{9}\)cách2 =\(\left(\frac{2}{3}\times\frac{4}{5}\right)\times\frac{5}{6}\)\(\frac{2}{3}\times\frac{4}{5}\times\frac{5}{6}\)=\(\frac{40}{90}\)=\(\frac{4}{9}\)

cách1\( \left(\frac{1}{2}+\frac{1}{3}\right)\times\frac{1}{5}\)= \(\frac{5}{6}\times\frac{1}{5}\)=\(\frac{1}{6}\)cách2\( \left(\frac{1}{2}+\frac{1}{3}\right)\times\frac{1}{5}\)=\(\frac{1}{2}\times\frac{1}{5}+\frac{1}{3}\times\frac{1}{5}\)=\(\frac{1}{10}+\frac{1}{15}\)=\(\frac{25}{150}\)=\(\frac{1}{6}\)

cách1\(\left(\frac{2}{3}\times\frac{4}{5}\right)\times\frac{5}{6}\)=\(\frac{2}{3}\times\left(\frac{4}{5}\times\frac{5}{6}\right)\)=\(\frac{2}{3}\times\frac{2}{3}\)=\(\frac{4}{9}\) cách 2 \(\left(\frac{2}{3}\times\frac{4}{5}\right)\times\frac{5}{6}\)=\(\frac{2}{3}\times\frac{4}{5}\times\frac{5}{6}\)=\(\frac{2\times4\times5}{3\times5\times6}\)=\(\frac{2\times4\times5}{3\times5\times2\times3}\)=\(\frac{4}{9}\)

cách1\(\left(1\times2+\frac{1}{3}\right)\times\frac{1}{5}\)=\(\frac{7}{3}\times\frac{1}{5}\)=\(\frac{7}{15}\) cách2\(\left(1\times2+\frac{1}{3}\right)\times\frac{1}{5}\)=\(1\times\left(2+\frac{1}{3}\right)\times\frac{1}{5}\)=\(1\times\frac{7}{3}\times\frac{1}{5}\)=\(\frac{7}{3}\times\frac{1}{5}\)=\(\frac{7}{15}\)

/HT\