Đáp án đúng : C

uses crt; 
var a, b: logint; 
Begin 
write('nhap so a ='); Readln(a); 
write('nhap so b ='); readln(b); 
If (a = 0 and b = 0) 
then write ('pt co nghiem x thuoc R') 
else 

(C++) 

#include <bits/stdc++.h>
using namespace std;
int main() {
int a, b;
double x;
cin >> a >> b;
cout << a << "x+" << b << "=0";
cout << "\n<=> x=" << (double)-b/a << endl;
return 0;
}

Chúc bn học tốt!

Bài đầy đủ hơn của mk (bn có thể tham khảo):

#include <bits/stdc++.h>
using namespace std;
int main() {
int a, b;
double x;
cin >> a >> b;
if(a==0) {
    {if(b!=0)
    cout << "Phuong trinh vo nghiem" << "\n";}
    {if(b==0)
    cout << "Phuong trinh co vo so nghiem" << "\n";} }
if (a!=0) {
{ if(b!=0)
   {cout << a << "x+" << b << "=0";
cout << "\n<=> x=" << (double)-b/a << "\n";} }
{
    if(b==0) {
    {
        cout << "x=0" << endl;}
    }
}
}
return 0;
}

Chúc bn học tốt!

uses crt;

var a,b,c,max:integer;

begin

clrscr;

write('nhap ba so:');readln(a,b,c);

if a mod 2=0 then writeln(a,' la so chan')

else writeln(a,'la so le);

if b mod 2=0 then writeln(b,'la so chan')

else writeln(b,'la so le');

if c mod 2=0 then writeln(c,'la so chan')

else writeln(c,'la so le');

max:=a;

if max<b then max:=b;

if max<c then max:=c;

writeln('so lon nhat trong ba so la:',max);

readln

end.

1:

uses crt;

const fi='ketqua.txt'

var f1:text;

st:string;

i,d:integer;

begin

clrscr;

assign(f1,fi); rewrite(f1);

write('Nhap xau:'); readln(st);

d:=length(st);

for i:=1 to d do 

 if st[i]=#32 then delete(st,i,1);

writeln(f1,st);

close(f1);

end.

2:

uses crt;

var a,b,c,d:integer;

{----------chuong-trinh-con-----------------------}

function min(x,y:integer):integer;

begin

if x<y then min:=x

else min:=y;

end;

{---------------chuong-trinh-chinh--------------------}

begin

clrscr;

write('a='); readln(a);

write('b='); readln(b);

write('c='); readln(c);

write('d='); readln(d);

writeln(min(a,min(b,min(c,d))));

readln;

end.

SOS:)

Bài 2: 

#include <bits/stdc++.h>;

using namespace std;

int main();

{

long m,n;

cout<<"Nhap m="; cin>>m;

cout<<"Nhap n="; cin>>n;

cout<<m*n-2;

return 0;

}

a)

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

      n,i,max,d:longint;

begin

read(n);

for i:=1 to n do

write('nhap chieu cao, don vi cm');read(a[i]);

b) max:=a[1];

for i:=2 to n do

if a[i]>max then max:=a[i];

writeln('ban cao nhat cao',max);

c) for i:=1 to n do

if a[i]>160 then d:=d+1;

write('so ban cao hon 160 cm la: ',d);

end.

uses crt;

var a:array[1..50]of real;

max:real;

i,n,dem:integer;

begin

clrscr;

write('Nhap so hoc sinh:'); readln(n);

for i:=1 to n do 

  begin

write('Nhap chieu cao cua ban thu ',i,':'); readln(a[i]);

end;

max:=a[1];

for i:=1 to n do 

  if max<a[i] then max:=a[i];

writeln('Chieu cao lon nhat la: ',max);

dem:=0;

for i:=1 to n do 

  if a[i]>1.6 then inc(dem);

writeln('So hoc sinh cao hon 1,6m la: ',dem);

readln;

end.

program hello;

uses crt;

Var n,i,j,k: integer;

a: array[1..50] of integer;

begin;

a[1]:=k;

Readln(n);

For i:=1 to n do

Begin;

Writeln('nhap a[',i,'] '); Readln(a[i]);

End;

For i:=1 to n-1 do

For j:=i+1 to n do

If a[i]<a[j] then k:=a[j];

Writeln('gia tri lon nhat la', k);

end.

Test 1: 

a=2; b=4

=>-2

Test 2: 

a=0; b=0;

=>Vô số nghiệm