Question

Tính hợp lý:

a, 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21

b,2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40

c,5 x 7 x 77 - 7 x 60 +49 x 25 -15 x 42.

 

Answer 1

a, 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21

= 53 x (39-21) + 47 x (93-21)

=53 x 18 + 47 x 18

= (53 +47) x 18

=100 x 18

=1800

b,2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40

=24 x 53 + 24 x 87 - 24 x 40

=24 x (53+87-40)

=24 x 100

=2400

c,5 x 7 x 77 - 7 x 60 +49 x 25 -15 x 42.

=5 x 7 x 77 - 7 x 5 x 12 +49 x 5 x 5 - 5 x 3 x 42.

=5 x 539 - 84 x 5 +245 x 5 -5 x 126

=5 x (539 - 84 +245 -126)

=5 x 574

=2870

Answer 2

tính nhanh cơ

Answer 3

a, 53 x 39 + 47 x 39 ‐ 53 x 21 ‐ 47 x 21
= 53 x ﴾39‐21﴿ + 47 x ﴾93‐21﴿
=53 x 18 + 47 x 18
= ﴾53 +47﴿ x 18
=100 x 18
=1800
b,2 x 53 x 12 + 4 x 6 x 87 ‐ 3 x 8 x 40
=24 x 53 + 24 x 87 ‐ 24 x 40
=24 x ﴾53+87‐40﴿
=24 x 100
=2400
c,5 x 7 x 77 ‐ 7 x 60 +49 x 25 ‐15 x 42.
=5 x 7 x 77 ‐ 7 x 5 x 12 +49 x 5 x 5 ‐ 5 x 3 x 42.
=5 x 539 ‐ 84 x 5 +245 x 5 ‐5 x 126
=5 x ﴾539 ‐ 84 +245 ‐126﴿
=5 x 574
=2870

Mi Su

Answer 4

tinh nhan phan c do

Answer 5

a) Ta có: 
53 . 39 + 47 . 39 - 53 . 21 - 47 . 21 + 2 . 53 . 12 + 4 . 6 . 87 - 3 . 8 . 40
= (53 + 47) . 39 - (53 + 47) . 21 + 24 . 53 + 24 . 87 - 24 . 40
= 100 . 39 - 100 . 21 + 24 . (53 + 87 - 40)
= 100 . (39 - 21) + 24 . 100
= 100 . (18 + 24)
= 100 . 42
= 4200
Vậy: = 4200

Answer 6

cho minh hoi 93 trong bai caca ban o dau ra vay

Answer 7

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