1:
uses crt;
var a,b:real;
begin
clrscr;
write('Nhap a='); readln(a);
write('Nhap b='); readln(b);
if a<>0 then writeln('Nghiem cua phuong trinh la: ',-b/a:4:2)
else writeln('Phuong trinh vo nghiem');
readln;
end.
2:
uses crt;
var n:real;
begin
clrscr;
write('Nhap n='); readln(n);
if n>=0 then writeln('Can bac hai cua n la: ',trunc(sqrt(n)))
else writeln(n,' khong co can bac hai');
readln;
end.
3:
uses crt;
var a,b,c:real;
begin
clrscr;
repeat
write('Nhap a='); readln(a);
write('Nhap b='); readln(b);
write('Nhap c='); readln(c);
until (a>0) and (b>0) and (c>0);
if (a+b>c) and (a+c>b) and (b+c>a) then writeln('Day la do dai ba canh trong mot tam giac')
else writeln('Day khong la do dai ba canh trong mot tam giac');
readln;
end.