KHO THE

\(A=\frac{\left[\left(25-1\right):1+1\right]\left(25+1\right)}{2}=325.\)

\(B=\frac{\left[\left(51-3\right):2+1\right]\left(51+3\right)}{2}=675\)

\(C=\frac{\left[\left(81-1\right):4+1\right]\left(81+1\right)}{2}=861\)

65 A

Dịch từng câu ta thấy câu A hợp nghĩa nhất: Hãy rửa tay của bạn thật đúng cách để ngăn ngừa virut corona

66 cleaning

Cấu trúc : spent time V-ing

\(a,A=\dfrac{1}{2010}-\dfrac{1}{2009}-\dfrac{1}{2009}+\dfrac{1}{2008}-...-\dfrac{1}{3}+\dfrac{1}{2}-\dfrac{1}{2}+1\\ A=1+\dfrac{1}{2010}=\dfrac{2011}{2010}\)

\(b,B=\left(-124\right)\left(63-37\right)+\dfrac{17}{66}\left(-66\right)=-124\cdot26+17=-3224+17=-3207\)

#include <bits/stdc++.h>

using namespace std;

int main()

{

int n,i,kt;

cin>>n;

cout<<pow((n*(n+1)/2),4);

}

bạn vào câu hỏi tương tự có thể có đấy

jup mik vs

mik tìm r k có

\(a.\left(\dfrac{2}{5}.\dfrac{5}{2}\right).\dfrac{10}{21}=1.\dfrac{10}{21}=\dfrac{10}{21}\)

\(\dfrac{1}{2}.4+\dfrac{3}{4}.4=2+3=5\)

a tính bằng cách là

( 2/5 x 5/2 ) x 10/21 

= 1 x 10/21 

10/21

b tính bằng cách là

1/2 + ( 3/4 x 4)

=1/2 x 12/4 rút gọn là 1/2 x 3

= 3/2

\(4x^4y^8+\left(x^2y^4\right)^4+4=4x^4y^8+x^8y^{16}+4\)

\(4x^4y^8+\left(x^2y^4\right)^4+4=\left(x^2y^4+2\right)^2\)

A = 0,(36) - 0,(71)

= 36/99 - 71/99

= -35/99

B = [3,(12) - 2,(5)] : 0,(14)

= (103/33 - 203/99) : 14/99

= 106/99 : 14/99

= 53/7

\(A=0,\left(36\right)-0,\left(71\right)\)

\(A=\dfrac{36}{99}-\dfrac{71}{99}=-\dfrac{35}{99}=-0,\left(35\right)\)

\(B=\left[3,\left(12\right)-2,\left(5\right)\right]:0,\left(14\right)\)

\(B=\left(\dfrac{3\cdot99+12}{99}-\dfrac{2\cdot9+5}{9}\right):\dfrac{14}{99}\)

\(B=\left(\dfrac{309}{99}-\dfrac{23}{9}\right):\dfrac{14}{99}\)

\(B=\dfrac{56}{99}:\dfrac{14}{99}\)

\(B=4\)

A=0,(36)-0,(71)

A=\(\dfrac{4}{11}\)-\(\dfrac{71}{99}\)

A=\(\dfrac{-35}{99}\)

B=[3,(12)-2,(5)]:0,(14)

B=[\(\dfrac{103}{33}\)-\(\dfrac{23}{9}\)]:\(\dfrac{14}{99}\)

B=\(\dfrac{-50}{33}\):\(\dfrac{14}{99}\)

B=\(\dfrac{-75}{7}\)

Ta có:

\(\dfrac{1}{x-y}+\dfrac{3xy}{y^3-x^3}+\dfrac{x-y}{x^2+xy+y^2}\\ =\dfrac{x^2+xy+y^2-3xy+\left(x-y\right)^2}{x^3-y^3}\\ =\dfrac{2\left(x-y\right)^2}{\left(x-y\right)\left(x^2+xy+y^2\right)}\\ =\dfrac{2\left(x-y\right)}{x^2+xy+y^2}\)

    \(\dfrac{1}{x-y}+\dfrac{3xy}{y^3-x^3}+\dfrac{x-y}{x^2+xy+y^2}\) \(=\dfrac{x^2+xy+y^2}{x^3-y^3}-\dfrac{3xy}{x^3-y^3}+\dfrac{\left(x-y\right)^2}{x^3-y^3}\)

\(=\dfrac{x^2+xy+y^2-3xy+x^2-2xy+y^2}{x^3-y^3}\)

\(=\dfrac{2x^2+2y^2-4xy}{x^3-y^3}\)

\(=\dfrac{2x^2-2xy-2xy+2y^2}{x^3-y^3}\)

\(=\dfrac{2x\left(x-y\right)-2y\left(x-y\right)}{x^3-y^3}\)

\(=\dfrac{\left(2x-2y\right)\left(x-y\right)}{\left(x-y\right)\left(x^2+xy+y^2\right)}\)

\(=\dfrac{2x-2y}{x^2+xy+y^2}\)

16-18+20-22+24-26+28-....-62+64-66+68

 = 16 +(20-18) + (24-22) + ( 28-26 ) +........+ (68-66)

 = 16 +2+2+2+.....+2

 = 16 + 2.26

 = 68