2,46+3,45+7,57

= ( 2,46+7,57)+3,45
=10+3,45

=13,45

b)5,03 + 12,48 + 4,97 + 17,52

=(5,03+4,97)+  (12,48+17,52)

=9,90   +   29,90

=39,80

ý a mình ko chắc đâu nhé hình như là lấy (3,45+7,57)+2,46 là xong

2,46

sai

C

`=` Chọn: `C`

a, \(=16,24\left(12-3+1\right)\)

\(=16,24.10=162,4\)

b, \(=1,25\left(1+2+7\right)\)

\(=1,25.10=12,5\)

c, \(=2,46\left(2+8\right)\)

\(=2,46.10=24,6\)

\(a,=16,24\times12-16,24\times3+16,24\times1\\ =16,24\times\left(12-3+1\right)=16,24\times10=162,4\\ b,=1,25\times\left(1+2+7\right)=1,25\times10=12,5\)

3,45 × 123 + 4 × 3,45 - 3,45 × 27

= 3,45 × (123+4-27)

= 3,45 × 100 = 345

a , 11 , 2 − 7 , 63 + 8 , 8 − 2 , 37 = 11 , 2 + 8 , 8 ⏟ − 7 , 63 + 2 , 37 ⏟ = 20 − 10 = 10 b , 3 , 45 × 123 + 4 × 3 , 45 − 3 , 45 × 27 = 3 , 45 × 123 + 4 − 3 , 45 × 27 = 3 , 45 × 127 − 3 , 45 × 27 = 3 , 45 × 127 − 27 = 3 , 45 × 100 = 345

a) 

11 , 2 − 7 , 63 + 8 , 8 − 2 , 37 = 11 , 2 + 8 , 8 ⏟ − 7 , 63 + 2 , 37 ⏟                                                                       = 20 − 10                                                                       = 10

b)

3 , 45 × 123 + 4 × 3 , 45 − 3 , 45 × 27 = 3 , 45 × 123 + 4 − 3 , 45 × 27 = 3 , 45 × 127 − 3 , 45 × 27 = 3 , 45 × 127 − 27 = 3 , 45 × 100 = 345

\(3,45\times0,99+3,45:100+3,45\times99\\ =3,45\times0,99+3,45\times0,01+3,45\times99\\ =3,45\times\left(0,99+0,01+99\right)\\ =3,45\times100\\ =345\)

\(3,45.3,2+3,45+3,45+3,45.4,8\)

\(=3,45\left(3,2+1+1+4,8\right)\)

\(=3,45.10\)

\(=34,5\)

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