Question

Tính nhanh:

a, 39 x 39 + 41 x 39 + 39 x 20

b, 428 x 75 + 5 x 428 -70 x 428

Answer 1

a/ = 39 x ( 39 + 41 + 20 )

= 39 x 100 = 3900

b/ = 428 x ( 75 + 5 - 70 )

= 428 x 10 = 4280

Answer 2

a) 39 x 39 + 41 x 39 + 39 x 20

= 39 x (39 + 41 + 20)

= 39 x 100

= 3900

b) 428 x 75 + 5 x 428 - 70 x 428

= 428 x (75 + 5 - 70)

= 428 x 10

= 4280

Answer 3

 

 

a, 39 x 39 + 41 x 39 + 39 x 20

=39x(41+20+39)

=39x 100

=3900

b, 428 x 75 + 5 x 428 -70 x 428

=428x (75+5-70)

=428x10

=4280