Giúp mình với pls mình cần vội lămd ai nhanh nhất cho 5 sao

#Ngocbich007

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A) 4/5 : 4/5 + 7/12 × 3/4 -1

= 4/5 × 5/4 + 7/4 × 1/4 -1

= 1 + 7/16 + (-1)

= [1+(-1)] + 7/16

= 0 +7/16 = 7/16

B) 9/5 × 1/2 - 2/5 ×1/4 + 4/5 × 1/2

= 1/5 × 9/2 - 1/5 × 2/4 + 1/5 × 4/2

= 1/5 × ( 9/2 - 2/4 + 4/2 )

= 1/5 × ( 18/4 - 2/4 + 8/4)

= 1/5 × 24/4

= 1/5 × 6/1 = 6/5

C) 3/7 + 5/4 - ( 3/7 + 13/4 ) + 1/2

= 3/7 +5/4 + (-3/7) + (-13/4) + 1/2

= [3/7 + (-3/7)] + [5/4 + (-13/4)] + 1/2

= 0 + 8/4 + 1/2 = 2 + 0,5 = 2,5

D) -5/13 + 7/4 + 4/9 - 8/13 + 1/4

= [-5/13 + (-8/13)] + (7/4 + 1/4) + 4/9

= -1 + 2 + 4/9 = 1 + 4/9 = 1 4/9 ( hỗn số )

E) 7/5 × 3/12 + 7/5 × 4/12 + 7/5 × 5/12

= 7/5 × ( 3/12 + 4/12 + 5/12 )

= 7/5 × 1 = 7/5

Chúc bạn học tốt