12-12/7-12/289-12/85 trên 4-4/7-4/289-4/85 chia cho 3/13+3/169+3/91 trên 7+7/13+7/169+7/91

0 bình luận về “12-12/7-12/289-12/85 trên 4-4/7-4/289-4/85 chia cho 3/13+3/169+3/91 trên 7+7/13+7/169+7/91”

1. $\dfrac{12-\dfrac{12}{7}-\dfrac{12}{289}-\dfrac{12}{85}}{4-\dfrac{4}{7}-\dfrac{4}{289}-\dfrac{4}{85}}:\dfrac{3+\dfrac{3}{13}+\dfrac{3}{169}+\dfrac{3}{91}}{7+\dfrac{7}{13}+\dfrac{7}{169}+\dfrac{7}{91}}$

   $=\dfrac{12\left(1-\dfrac{1}{7}-\dfrac{1}{289}-\dfrac{1}{85}\right)}{4\left(1-\dfrac{1}{7}-\dfrac{1}{289}-\dfrac{1}{85}\right)}:\dfrac{3\left(1+\dfrac{1}{13}+\dfrac{1}{169}+\dfrac{1}{91}\right)}{7\left(1+\dfrac{1}{13}+\dfrac{1}{169}+\dfrac{1}{91}\right)}$

   `=12/4:3/7`

   `=3:3/7`

   `=7`

   Trả lời

2. Đáp án:   `7`

    

   Giải thích các bước giải:

   Cách 1:

   `(12-12/7-12/289-12/85 )/(4-4/7-4/289-4/85 ):(3/13+3/169+3/91 )/( 7+7/13+7/169+7/91)`

   Ta có :

   `(12-12/7-12/289-12/85 )/(4-4/7-4/289-4/85 )`

   `=[12(1-1/7-1/289-1/85 )]/[4(1-1/7-1/289-1/85 )]`

   `=12/4=3(1)`

   Ta có :

   `(3/13+3/169+3/91 )/( 7+7/13+7/169+7/91)`

   `=[3(1/13+1/169+1/91 )]/[ 7(1+1/13+1/169+1/91)`

   `=3/7(2)`

   Vì `(12-12/7-12/289-12/85 )/(4-4/7-4/289-4/85 ):(3/13+3/169+3/91 )/( 7+7/13+7/169+7/91)`

   nên `(1):(2)`

   `=3:3/7`

   `=3. 7/3`

   `=7`

   Cách 2 :

   `(12-12/7-12/289-12/85 )/(4-4/7-4/289-4/85 ):(3/13+3/169+3/91 )/( 7+7/13+7/169+7/91)`

   `=[12(1-1/7-1/289-1/85 )]/[4(1-1/7-1/289-1/85 )]:[3(1/13+1/169+1/91 )]/[ 7(1+1/13+1/169+1/91)`

   `=12/4:3/7`

   `=3:3/7`

   `=3. 7/3`

   `=7`

   Trả lời