Câu 21: A.LayOut

Câu 3: C

5: Thay x=21 và y=3000 vào y=ax+b, ta được:

a*21+b=3000

=>21a+b=3000

Thay x=21-1=20 và y=3000+30=3030 vào y=ax+b, ta được:

20a+b=3030

=>21a+b-20a-b=3030-3000

=>a=30

21a+b=3000

=>b+630=3000

=>b=3000-630=2370

Vậy: y=30x+2370

#include <bits/stdc++.h>

using namespace std;

long long n,i,s;

int main()

{

cin>>n;

s=0;

for (i=1; i<=n; i++)

s=s+i;

cout<<s;

return 0;

}

b d b b c a

Question 1: B
Question 2: D
Question 3: B
Question 4: B
Question 5: C
Question 6: A

Program Tin_hoc;

Uses crt; 

Var i,n,dem:integer;

      a:array[1..100000] of integer;

Begin

clrscr;

Write('Nhap 1 so nguyen duong n: ');readln(n);

dem:=0;

Writeln('Nhap ',n,' phan tu:');

For i:= 1 to n do 

Begin

Write('A[',i,'] = ');

readln(a[i]);

If a[i] mod 2 = 0 then inc(dem);

End;

Writeln('Day vua nhap la:');

For i:= 1 to n do write(a[i],'  ');writeln;

Writeln('Day so vua nhap co ',dem,' so chan');

readln;

End.

uses crt;

var a:array[1..100]of integer;

i,n,dem:integer;

begin

clrscr;

write('Nhap n='); readln(n);

for i:=1 to n do 

  begin

write('A[',i,']='); readln(a[i]);

end;

for i:=1 to n do 

 write(a[i]:4);

writeln;

dem:=0;

for i:=1 to n do 

  if a[i] mod 2=0 then inc(dem);

writeln('So so chan la: ',dem);

readln;

end.