Đáp án:
`1`
`a)`
`A = ( 1374 x 57 + 687 x 86 ) : ( 26 x 13 + 74 x 14)`
`= ( 78318 +50982 ) : ( 338 + 1036)`
`= 129300 : 1374`
`= (21550)/(229)`
`b) B = ( 2 + 4 + 6 +......+ 100 ).(36 x 333 - 108 x 111)`
`= ( 2 + 4 + 6 +......+ 100 ) x (11988 - 11988)`
`= ( 2 + 4 + 6 +......+ 100 ) x 0`
`= 0 `
`d) D = 2/(3x5) + 2/ (5 x 7) + 2 / (7 x 9) +.......+ 2 /(97x 99)`
`= 1/3 - 1/5 + 1/5 - 1/7 + 1/7 - 1/9 + ... + 1/97 - 1/99`
`= 1/3 - 1/99`
`= 32/99`
Học tốt !