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`
