Question

Tính bằng cách thuận tiện nhất

A) 4/9+3/8+5/8

B) 3/7+2/3+4/7

Answer 1

A,  4/9 + [3/8 + 5/8 ]

    =4/9 + 1

    =13/9

B,  [3/7+4/7]+2/3

=1+2/3

=5/3

Answer 2

\(a)\frac{4}{9}+\frac{3}{8}+\frac{5}{8}=\frac{4}{9}+(\frac{3}{8}+\frac{5}{8})=\frac{4}{9}+1=\frac{4+9}{9}=\frac{13}{9}\)

\(b)\frac{3}{7}+\frac{2}{3}+\frac{4}{7}=(\frac{3}{7}+\frac{4}{7})+\frac{2}{3}=1+\frac{2}{3}=\frac{3+2}{3}=\frac{5}{3}\)

Answer 3

\(a,\frac{4}{9}+\frac{3}{8}+\frac{5}{8}\)

\(=\left(\frac{3}{8}+\frac{5}{8}\right)+\frac{4}{9}\)

\(=1+\frac{4}{9}\)

\(=\frac{9}{9}+\frac{4}{9}=\frac{13}{9}\)

\(b,\frac{3}{7}+\frac{2}{3}+\frac{4}{7}\)

\(=\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{2}{3}\)

\(=1+\frac{2}{3}\)

\(=\frac{3}{3}+\frac{2}{3}=\frac{5}{3}\)