Question

Tính hợp lý : 

12 x 78 - 24 x19

Answer 1

12 x 78 - 24 x 19 

= 12 x 78 -  12 x 2 x 19

= 12 x 78 -  2 x 19 

= 12 x 78 -  (2 x 9)

= 12 x 78 -  38

= 12 x (78 - 38)

= 12 x 40 

= 480

Answer 2

12x78-24x19

=12x78-12x(2x19)

=12x78-12x38

=12x(78-38)

=12x40

=480

Answer 3

12 x 78 - 24 x 19

= 12 x 78 - ( 12 + 12 ) x 19

= 12 x 78 - 12 x 19 + 12 x 19

= 12 x ( 78 - 19 + 19 )

= 12 x 78

= 936

Answer 4

\(12x78-24x19\)

\(=12x78-12x2x19\)

\(=12x78-2x19\)

\(=12x78-38\)

\(=12x\left(78-38\right)\)

\(=12x40\)

\(=480\)

Chúc bạn học tốt Ngo khanh huyen !

Answer 5

12x78-24x19=12x78-2x12x19

                   = 12x78-12x38

                    = 12x (78-30)

                  =    600