1. = 1+2+3/7 = 6/7
2. = (3/7+4/7) + (4/9+5/9) = 1+1 = 2
Tk mk nha
\(\frac{1}{7}+\frac{2}{7}+\frac{3}{7}=\frac{1+2+3}{7}=\frac{6}{7}\)
\(\frac{3}{7}+\frac{4}{9}+\frac{4}{7}+\frac{5}{9}\)
\(=\left(\frac{3}{7}+\frac{4}{7}\right)+\left(\frac{4}{9}+\frac{5}{9}\right)\)
\(=1+1\)
\(=2\)
1) \(\frac{1}{7}+\frac{2}{7}+\frac{3}{7}=\frac{6}{7}\)
2) \(\frac{3}{7}+\frac{4}{9}+\frac{4}{7}+\frac{5}{9}\)
\(=\left(\frac{3}{7}+\frac{4}{7}\right)+\left(\frac{5}{9}+\frac{4}{9}\right)\)
\(=\frac{7}{7}+\frac{9}{9}\)
\(=1+1=2\)