Question

[TTT . boy]

tính hợp lý

a) \(\left(\frac{-1}{3}\right)\). \(\frac{9}{11}+\left(\frac{-8}{9}\right).27\)

b) \(\left(\frac{1}{2}-\frac{13}{14}\right)\): \(\frac{5}{7}-\left(-\frac{-2}{21}+\frac{1}{7}\right):\frac{5}{7}\)

Answer 1

[Trần Thu Huyền]

a . ( -1/3 ) . 9/11 + ( -8/9 ) . 27

= 9/3 . ( -1/11 ) + 27/9 . ( -8 )

= 3 . ( -1/11 ) + 3 . ( -8 )

= 3 . ( -1/11 + ( -8 ) )

= 3 . ( -89/11 )

= -267/11

b . ( 1/2 - 13/14 ) : 5/7 - ( - - 2/21 + 1/7 ) : 5/7

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

= ( -3/7 - 5/21 ) : 5/7

= -2/3 : 5/7

= -14/15