20. Ділення дробів - 21. Знаходження дробу » 890

Обчисли значення виразу. а) (9 1/6 ∶ 3 3/4 + 4 1/3 ∶ 3 1/4 - 7/(5 ) ∶ 1 4/5)/(5 1/8 ∶ 20 1/2 + 5/(6 ) ∶ 1 2/3) = (55/6 ∶ 15/4 + 13/3 ∶ 13/4 - 7/(5 ) ∶ 9/5)/(41/8 ∶ 41/2 + 5/(6 ) ∶ 5/3) = (55/6 • 4/15 + 13/3 • 4/13 - 7/(5 ) • 5/9)/(41/8 • 2/41 + 5/(6 ) • 3/5) = (22/9 + 4/3 - 7/(9 ))/(1/4 + 1/(2 )) = (22/9 + 12/9 - 7/(9 ))/(1/4 + 2/(4 )) = (27/9)/(3/4) = 3 • 4/3 = 4. б) (2/3 ∶ 〖(2/3)〗^2+ 1,5 - 4/(5 ) ∶ 1 3/(5 ))/(〖(3/4)〗^2 • 2 2/3 + 1 5/(7 ) ∶ 3/(14 ) - 9 1/(8 )) = (2/3 ∶ 4/9 + 1 1/2 - 4/(5 ) ∶ 8/(5 ))/(9/16 • 8/3 + 12/(7 ) ∶ 3/(14 ) - 73/(8 )) = (2/3 • 9/4 + 3/2 - 4/(5 ) • 5/(8 ))/(9/16 • 8/3 + 12/(7 ) • 14/(3 ) - 73/(8 )) = (3/2 + 3/2 - 1/(2 ))/(3/2 + 8 - 73/(8 )) = (5/2)/(12/8 + 64/8 - 73/(8 )) = (5/2)/(3/8) = 5/2 • 8/3 = 20/3 = 62/3.