Số bị chia là: 258- 5 - 8 = 245

Số chia là: ( 145 - 5) : 8 = 30

Số bị chia là:

258- 5 - 8 = 245

Số chia là:

( 145 - 5) : 8 = 30

A= 81 = 9²

a, 3 mũ 4

TL:

1+7+8+15+23+...+160= 1+(8-1)+ (15-7)+ (23-8)+(38-15)+(61-23)+(99-38)+(160-61)+(259-99) =-7+160+259 =412

Gọi tập hợp đó là B

B = { 10; 11; 12; 20; 21; 22 }

Tập hợp B là :

B = { 10;11;12;21;21;22 }

\(A=\left\{0;2\right\}\\ B=\left\{0;6;12;18;24\right\}\)

A = { 2}               B ={ 6;12;18;24}

\(\dfrac{5b}{4}=\dfrac{5}{8.13}+\dfrac{5}{13.18}+\dfrac{5}{18.23}+...+\dfrac{5}{253.258}\\ =\dfrac{1}{8}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{18}+\dfrac{1}{18}-\dfrac{1}{23}+...+\dfrac{1}{253}-\dfrac{1}{258}\\ =\dfrac{1}{8}-\dfrac{1}{258}=\dfrac{125}{1032}\\ =>b=\dfrac{25}{258}\)

\(B=\dfrac{4}{8\cdot13}+\dfrac{4}{13\cdot18}+\dfrac{4}{18\cdot23}+...+\dfrac{1}{253\cdot258}\)

\(B=4\left(\dfrac{1}{8\cdot13}+\dfrac{1}{13\cdot18}+\dfrac{1}{18\cdot23}+...+\dfrac{1}{253\cdot258}\right)\)

\(B=\dfrac{4}{5}\left(\dfrac{5}{8\cdot13}+\dfrac{5}{13\cdot18}+\dfrac{5}{18\cdot23}+...+\dfrac{5}{253\cdot258}\right)\)

\(B=\dfrac{4}{5}\left(\dfrac{1}{8}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{18}+\dfrac{1}{18}-\dfrac{1}{23}+...+\dfrac{1}{253}-\dfrac{1}{258}\right)\)

\(B=\dfrac{4}{5}\left(\dfrac{1}{8}-\dfrac{1}{258}\right)\)

\(B=\dfrac{4}{5}\cdot\dfrac{125}{1032}=\dfrac{25}{258}\)

cái thứ nhất bằng -2985871

cái thứ hai bằng 16

\(\left\{{}\begin{matrix}x⋮12\\x⋮21\end{matrix}\right.\) =>\(x\in BC\left(12;21\right)\)

Ta có: 12= \(2^2\cdot3\)

            21 = 3*7

=> BCNN(12;21)= 2² *3*7= 84

BC(12;21)=B(84)={0;84;168;252;336;420;504;....}

Vì 18<x<500 =>x\(\in\left\{84;168;252;336;420\right\}\)

\(5.5.125^2=5.5.\left(5^3\right)^2=5.5.5^{3.2}=5^1.5^1.5^6\\ =5^{1+1+6}=5^8\)

5. 5. 125^2 

= 25 . 15625

= 390625

A = { 0;1;2;3;4;5}

A= { x\(\in\) \(ℕ\) | x \(\le\) 5}