Question

Thực hiện phép tính ( tính nhanh nếu có thể ):

a, ( 1/2 - 13/14 ) : 5/7 - ( -2/21 + 1/7 ) : 5/7

b, ( 68/5 + 19/4 ) - 43/5

c, ( 93/11 + 29/8 ) - 38/11

d, 4/9 : ( -1/7 ) +59/9 : ( -1/7)

Answer 1

a, ( 1/2 - 13/14 ) : 5/7 - ( -2/21 + 1/7 ) : 5/7

= ( 7/14 - 13/14 ) : 5/7 - ( -2/21 + 3/21 ) : 5/7

= -3/7 : 5/7 - 1/21 : 5/7

= -3/7 . 7/5 - 1/21 . 7/5

= ( -3/7 - 1/21 ) . 7/5

= ( -9/7+ -1/21 ) . 7/5

= -10/21 . 7/5

= -2/3

b, (68/5 + 19/4 ) - 43/5

= 68/5 + 19/4 - 43/5

= ( 68/5 - 43/5 ) + 19/4

= 5 +19/4

= 39/4

c, ( 93/11 + 29/8 ) - 38/11

= 93/11 + 29/8 - 38/11

= ( 93/11 - 38/11 ) + 29/8

= 5 + 29/8

=69/8

d, 4/9 : ( -1/7 ) + 59/9 : ( -1/7 )

= 4/9 . -7 + 59/9 . -7

= ( 4/9 + 59/9 ) . -7

= 7 . -7

= -49