Question

tính một cách hợp lý :

21 . 35 - 3 . 25 . 7 

77 - 11 ( 30 + 7 )

85 ( 35 - 27 ) - 35 ( 85 - 27 )

47 ( 45 - 15 ) - 47 ( 45 + 15 )

Answer 1

21.35-3.25.7

= 21.35-21.25

= 21.(35-25)

= 21. 10

=210

77 - 11.( 30+7)

= 11.7 -11.30 -11.7

= 11.7-11.7 -11.30

= -11.30

= -330

Answer 2

21.35-3.25.7=210

77-11(30+7)=-330

85(35-27)-35(85-27)=-1350

47(45-15)-47(45+15)=-2820

Answer 3

a)21.35-3.25.7

=21.35-(3.7).25

=21.35-21.25

=21.(35-25)

=21.10=210

Answer 4

Dễ qúa !!!!