Question

Bài 1 . Tính nhanh :

A = 6/7 + 1/7 . 2/7 + 1/7 . 5/7

B = 4/9 . 13/3 - 4/3 . 40/9

M = 8/3 . 2/5 . 3/8 . 10 . 19/2

N = 5/7 . 5/11 + 5/7 . 2/11 - 5/7 . 14/11

Answer 1

B=4*13/9*3-4/3*40/9

B=4/3*13/9-4/3*40/9

B=4/3*(13/9-40/9)

B=4/3*(-27)/9

B=4*(-3)/9

B=-4

Answer 2

A=6/7 + 1/7.(2/7+5/7)

A=6/7 + 1/7.7/7=6/7+1/7.1

A=6/7+1/7=7/7=1

Answer 3

M=8/3*2/5*3/8*10*19/2

M=(8/3*3/8)*(2/5*10)*19/2

M=1*4*19/2

M=28