Question

вычислите а) 2/5+1/2, б) 5/6-2/3, в) 8/15+3/10

Answer 1

$frac{2}{5} + frac{1}{2} = frac{2*2}{5*2} + frac{1*5}{2*5} = frac{4}{10} + frac{5}{10} = frac{4+5}{10} = frac{9}{10}$

$frac{5}{6} - frac{2}{3} = frac{5}{6} - frac{2*2}{3*2} = frac{5}{6} - frac{4}{6} = frac{5-4}{6} = frac{1}{6}$

$frac{8}{15} + frac{3}{10} = frac{8*2}{15*2} + frac{3*3}{10*3} = frac{16}{30} + frac{9}{30} = frac{16+9}{30} = frac{25}{30} = frac{25:5}{30:5} = frac{5}{6}$