A= (357-62)-(-62-643)

=375-62+62+643

=1018     

1 đúng nha

(357-62)-(-62-643)

= 357- 62 + 62 - 643

= 62(357- 643)

=-17732

a; A = 7^2007-5.7^2005+4.7^2004 chia hết cho 13

A = 7^2004.(7^3 - 5.7 + 4)

A = 7^2004.(343 - 35 + 4)

A = 7^2004.(298 + 4)

A = 7^2004.312

A = 7^2004.13.24

Vì 13 chia hết cho 13 nên A chia hết cho 13 đpcm

Câu 2:Tìm số nguyên x,biết:

a/x-3 chia hết cho 3x-2

Giải

(x - 3) ⋮ (3x - 2)

(3x - 9) ⋮ (3x - 2)

(3x - 2 - 7) ⋮ (3x - 2)

7 ⋮ (3x - 2)

(3x - 2) ∈ Ư(7) = {-7; -1; 1; 7}

\(x\in\) {-5/3; 1/3; 1; 3}

Vì \(x\in\) Z nên \(x\) ∈ {1; 3}

Vậy \(x\) ∈ {1; 3}

100 + 567 = 667

134 + 643 = 777

3424 + 445 = 3869

đây là toán lp 2 mà

100+567= 667

134+643= 777

3424+445= 3869

Mà sao đây toán lớp 7 được?

357⁷:357⁶=357^7-6=357¹=357

544+64+100%=608+1=609

357⁷:357⁶=357^7-6=357¹=357

544+64+100%

=544+64+1

=608+1

=609

Câu 1:

a) \(\left(\dfrac{4}{8}+\dfrac{1}{2}\right):\left(\dfrac{3}{5}-\dfrac{8}{7}\right)\)

\(=\left(\dfrac{1}{2}+\dfrac{1}{2}\right):\left(\dfrac{21}{35}-\dfrac{40}{35}\right)\)

\(=1:\dfrac{-19}{35}\)

\(=\dfrac{35}{-19}\)

b) \(-1\dfrac{3}{5}+0,34-50\%\)

\(=-\dfrac{8}{5}+\dfrac{34}{100}-\dfrac{50}{100}\)

\(=-\dfrac{160}{100}+\dfrac{34}{100}-\dfrac{50}{100}\)

\(=-\dfrac{44}{25}\)

Câu 2:

A = 357 - 62 - (-62 - 643)

A = 357 - 62 + 62 + 643

A = (357 + 643) - (62 - 62)

A = 1000 - 0

A = 1000

Câu 3:

\(\left(\dfrac{x}{5}-1\right):\left(-5\right)=\dfrac{1}{10}\)

\(\dfrac{x}{5}-1=\dfrac{1}{10}.\left(-5\right)\)

\(\dfrac{x}{5}-1=\dfrac{-1}{2}\)

\(\dfrac{x}{5}=\dfrac{-1}{2}+1\)

\(\dfrac{x}{5}=\dfrac{1}{2}\Rightarrow x=\dfrac{1.5}{2}=2,5\)

=> x : 27 = 702 - 643 = 59

=> x = 59 x 27 = 1593

x : 27 + 643 = 702

x : 27          = 702 - 643

x : 27          = 59

x                = 1593

100 + 357 + 2 

= 457 + 2 

= 459

k cho mk nha bn

100+357+2=459

tk mình nha

= 3570

= 357x(5-1+6) = 357 x10 = 3570