hok bé ơi

 abcd + abc,d = 8 286,3

⇒ 7 962 + 324, 3 = 8 286, 3

 abc,d - ab,cd = 403, 29

⇒ 424, 09 - 20, 80 = 403, 29

Mong giúp ích cho bạn ^^

Ta có: $4=2^2$

          $7=7$

          $9=3^2$

$\Rightarrow BCNN(4,7,9)=2^2\cdot 3^2\cdot 7=252$

Của bn nha

BCNN(4;7;9)=252

3x = 147

x = 147 : 3 = 49

26 - ( 5 + 3x ) = 12

5 + 3x = 26 - 12 = 14

3x = 14 - 5 = 9

x = 9 : 3 = 3

3x = 147

x = 147 : 3 = 49

26 - ( 5 + 3x ) = 12

5 + 3x = 26 - 12 = 14

3x = 14 - 5 = 9

x = 9 : 3 = 3

Đặt: \(A=2+2^2+2^3+2^4+...+2^{100}\)

\(\Rightarrow\)\(2A=2^2+2^3+...+2^{101}\)

\(\Rightarrow2A-A=\left(2^2+2^3+...+2^{101}\right)-\left(2+2^2+...+2^{100}\right)\)

\(\Rightarrow\)\(A=2^{101}-2\)

Ta có ( 4x + 5 ) ⋮ ( 2x + 1 ) 

⇒ ( 4x + 2 + 3 ) ⋮ ( 2x + 1 ) 

Vì ( 4x + 2 ) ⋮ ( 2x + 1 ) ⇒ 3 ⋮ ( 2x + 1 ) hay ( 2x + 1 ) ϵ Ư( 3 ) = { 1; 3 }

Nếu 2x + 1 = 1 ⇒ x = 0

Nếu 2x + 1 = 3 ⇒ x = 1

Vậy x ϵ { 0; 1 } để ( 4x + 5 ) ⋮ ( 2x + 1 ) 

a.UCLN(45;120;90) = 15

Ta có UCLN(45;120;90) = 15 thì UC(45;120;90) là U(15)

U(15) = { 1 ;3 ;5 ;15}

UC(45;120;90) = { 1; 3; 5; 15}

b. UCLN(35,70,175) = 35

Ta có UCLN(35,70,175) = 35 THÌ UC(35,70,175) là U(35)

U(35) = {1; 5; 7; 35}

UC(35;70;175) = {1; 5; 7; 35}

a) ta có:

45=3^2x5

120=2^3x3x5

90=2x3^2x5

=ước chung lớn nhất (45,120,90)=2x3x5=30

= ước chung (45,120,90)=1;2;3;5;6;10;15;30

b)ta có 

35=5x7

70=2x5x7

175=5^2x7

= ước chung lớn nhất (35,70,175)=5x7=35

=ước chung (35,70,175)=1;5;7;35.

(-87) + (-12) + 487 + (-512)

= [(-87) + 487] + [(-12) + (-512)

= 400 + (-524)

= 124.

  Chúc bạn hok tốt

(-87) + (-12) + 487 + (-512)

= [(-87) + 487] + [(-12) + (-512)]

= 400 + (-524)

= -124     Mong lời giải của mình giúp ích cho bạn ^^

6¹⁶ : 6⁷ = 6⁹

Câu 1:

\(A=-7^{49}-\left\{-223-[-123-(200-7^{49})+2023]\right\}\)

\(=-7^{49}+223+[-123-(200-7^{49})+2023]\)

\(=-7^{49}+223-123-(200-7^{49})+2023\)

\(=-7^{49}+(223-123)-200+7^{49}+2023\)

$=(-7^{49}+7^{49})+(223-123)-200+2023$

$=0+100-200+2023=2023-100=1923$

------------------

$3B=1.2.3+2.3.3+3.4.3+....+80.81.3$

$3B=1.2.3+2.3(4-1)+3.4(5-2)+...+80.81(82-79)$

$3B=1.2.3+2.3.4+3.4.5+...+80.81.82-(1.2.3+2.3.4+...+79.80.81)$

$3B=80.81.82$
$\Rightarrow B=\frac{80.81.82}{3}$

-------------------------

\(C=\frac{2^{12}.(3^2)^4-3^9.(2^3)^4}{2^{13}.2^8-(2^3)^4.(3^3)^3}=\frac{2^{12}.3^8-3^9.2^{12}}{2^{21}-2^{12}.3^9}\)

\(=\frac{2^{12}.3^8(1-3)}{2^{12}(2^9-3^9)}=\frac{-2.3^8}{2^9-3^9}=\frac{2.3^8}{3^9-2^9}\)

Câu 2:

$3.49^x=35.7^{2023}-14.7^{2023}$

$3.(7^2)^x=5.7.7^{2023}-2.7.7^{2023}$

$3.7^{2x}=5.7^{2024}-2.7^{2024}=7^{2024}(5-2)=3.7^{2024}$

$\Rightarrow 7^{2x}=7^{2024}$

$\Rightarrow 2x=2024$
$\Rightarrow x=1012$