Tính thuận tiện :
19,76 x 98,68 - 19,76 x 36,49 + 19,76 x 37,81
= ( 98,68 - 36,49 + 37,81 ) x 19,76
= 100 x 19,76
= 1976.
.>>>>>

Tính thuận tiện :

19,76 x 98,68 - 19,76 x 36,49 + 19,76 x 37,81

= ( 98,68 - 36,49 + 37,81 ) x 19,76

=          100 x 19,76

=              1976.

nếu đc thì t*** mk nhé!!!!

ính bằng cách thuận tiện nhất:

0.5 x 17 x 5 + 0.25 x 520 + 31 x 2.5

=>2,5x17+2.5x52+2,5x31

=2,5(17+52+31)

=2,5x100

=250

\(0,5\times17\times5\times0,25\times520+31\times2,5\)

\(\Rightarrow2,5\times17+2,5\times52+2,5\times31\)

\(\Rightarrow2,5\times\left(17+52+31\right)\)

\(\Rightarrow2,5\times100\)

\(\Rightarrow2500\)

2021 x 2021 - 2019 x 2023 

= (2019 +2) x ( 2023 -2) - 2019 x 2023

= 2019 x 2023 - 2 x 2019 + 2 x 2023 - 4 - 2019 x 2023

= ( 2019 x 2023 - 2019 x 2023) + 2 x ( 2023 - 2019) - 4

= 0 + 2 x 4 - 4

= 8 - 4

 = 4

2021 x 2021 - 2019 x 2023 

= (2019 +2) x ( 2023 -2) - 2019 x 2023

= 2019 x 2023 - 2 x 2019 + 2 x 2023 - 4 - 2019 x 2023

= ( 2019 x 2023 - 2019 x 2023) + 2 x ( 2023 - 2019) - 4

= 0 + 2 x 4 - 4

= 8 - 4

 = 4

a)8,3 x 6,9 + 8,3 + 2,1 x 8,3

= 8,3 x ( 6,9 + 2,1+1)

= 8,3 x 10

=83

b)

x+x\(\times\)2+x\(\times\)3=1,23

x\(\times\)(1+2+3)=1,23

x\(\times\)6=1,23

x=1.23:6

x=0,205

10,05 x 15,7-10,05 x 4,7-10,05

=10,05 x 15,7-10,05 x 4,7 - 10,05 x 1

=10,05 x (15,7-4,7-1)

=10,05 x 10

=100,5

10,05 x 15,7 - 10,05 x 4,7 - 10,05 = 10,05 x (15,7 - 4,7 - 1)

= 10,05 x 10

= 100,5

12,12 x 7,5 + 12,12 : 2 + 12,12 + 12,12

= 12,12 x 7,5 + 12,12 x 0,5 + 12,12 x 1 + 12,12 x 1

= 12,12 x (7,5 + 0,5 + 1 + 1)

= 12,12 x 10

= 121,2

121,2 nha bạn

=4,7.(15,6-11,4)+4,2.5,3

=4,7.4,2+4,2.5,3

=4,2.(4,7+5,3)

=4,2.10

=42

a) 0,25x3/4-0,25x0,25+0,25x1/2

=0,25x(3/4-0,25+1/2)

=0,25x1

=0,25

b) 5,68x8+56,8x0,1+56,8:10

=5,68x8+5,68+5,68

=5,68x(8+1+1)

=5,68x10

=56,8