Question

Помогите решить :
1. 7/10+7/9x27/35
2. 5/14+3/8x16/21
3. 3/16x4/7+5/8x6/35
4. 1+3/5x1 5/6
5. 5/12-8/21x7/16
6. 2-7/8x1 1/7

Answer 1

$frac{7}{10} + frac{7}{9} * frac{27}{35} = frac{7}{10} + frac{7*(3*9)}{9*(5*7)}= frac{7}{10} + frac{3}{5} = frac{7}{10} +frac{3*2}{5*2} = frac{7+6}{10} =frac{13}{10} =1 frac{3}{10} \ \ frac{5}{14} + frac{3}{8} * frac{16}{21} = frac{5}{14} + frac{3*(2*8)}{8*(3*7)} = frac{5}{14} + frac{2}{7} = frac{5}{14} + frac{2*2}{7*2} = frac{5+4}{14} = frac{9}{14}$

$frac{3}{16} * frac{4}{7} + frac{5}{8} * frac{6}{35} = frac{3*4}{(4*4)*7} + frac{5*2*3}{(2*4)*(5*7)} = frac{3*1}{1*4*7} + frac{1*1*3}{4*7} = \ \ = frac{3}{28} + frac{3}{28} = frac{6}{28} = frac{6:2}{28:2} = frac{3}{14} \ \ 1 + frac{3}{5} * 1 frac{5}{6} = 1 + frac{3}{5} * frac{1*6+5}{6} = 1 + frac{3}{5} * frac{11}{6} = 1+ frac{11}{10} = 1 + 1frac{1}{10} =2 frac{1}{10}$

$frac{5}{12} - frac{8}{21} * frac{7}{16} = frac{5}{12} - frac{8*7}{(3*7)*(2*8)} = frac{5}{12} -frac{1}{3*2} = frac{5}{12} - frac{1}{6} = frac{5-2}{12}= frac{3}{12} = frac{1}{4} \ \ 2 - frac{7}{8} *1 frac{1}{7} = 2 - frac{7}{8} * frac{1*7+1}{7} =2 - frac{7}{8} * frac{8}{7} = 2 - 1 = 1$