câu 1:

program pitago;
uses crt;
var a, b, c : integer;
begin clrscr;
write('nhap so nguyen a :');readln(a);
write('nhap so nguyen b :');readln(b);
write('nhap so nguyen c :');readln(c);
if (sqr(a) = sqr(b) + sqr(c)) or (sqr(b) = sqr(a) + sqr(c)) or (sqr(c) = sqr(b) + sqr(a)) then
writeln('ba so nguyen a, b, c la 3 so pitago')
else writeln('ba so nguyen a, b, c khong phai la 3 so pitago');
readln
end.

câu 2:

program tinh;
uses crt;
var a,b,x:real;
begin
clrscr;
writeln('nhap a: '); readln( a);
write(' nhap b: '); readln( b);
if ((a=0 ) and (b=0)) then write('phuong trinh vo so nghiem') 
else 
if ((a=0) and (b<>0)) then write('pt vo nghiem') 
else
begin
x:=-b/a;
write('phuong trinh  co nghiem x :',x:8:2);
readln;
end;
end.

Câu 3:

program max;
uses crt;
var a, b, c, d: integer;
begin
clrscr;
write('nhap so a :'); readln(a);
write('nhap so b :'); readln(b);
write('nhap so c :'); readln(c);
write('nhap so d :'); readln(d);
if (a>b) and (a>c) and (a>d) then writeln(a,' la so lon nhat');
if (b>a) and (b>c) and (b>d) then writeln(b,' la so lon nhat');
if (c>a) and (c>b) and (c>d) then writeln(c,' la so lon nhat');
if (d>a) and (d>b) and (d>c) then writeln(d,' la so lon nhat');
readln
end.