Còn bài 2,3 làm nốt

`@` Bài 2:

Program baitap;
Uses crt;
Var a,b:real;
Begin
Clrscr;
Write('a='); Readln(a);
Write('b='); Readln(b);
If(a=0) then
     If(b=0) then Writeln('Vo so nghiem')
     Else Writeln('Vo nghiem')
Else Writeln('x=',-b/a:5:2); 
Readln
End.

`@`Bài 3:

Program baitap;
Uses crt;
Var a,b,c,de:real;
Begin
Clrscr;
Write('a='); Readln(a);
Write('b='); Readln(b);
Write('c='); Readln(c);
de:=b*b+4*a*c;
If de<0 then writeln('Vo nghiem')
Else Begin
     Writeln('x1=', (-b+sqrt(de))/(2*a):5:2);
     Writeln('x1=', (-b-sqrt(de))/(2*a):5:2);
     End;
Readln
End.

_________________________

Đã test code

mik làm bài 1 và 4 nhé!

Bài 1:

uses crt;

var a,b,c,max: real;

begin

clrscr;

write('Nhap a,b,c:');

readln(a,b,c);

max:=a;

if max<b then max:=b;

if max<c then max:=c;

write('So lon nhat la: ',max);

readln

end.

Bài 4:

Uses crt;

Var a, b: real;

Begin

Clrscr;

Writeln (‘Luong dien tieu thu trong 1 thang:’);

Readln(a);

If a<=100 then b:=(550*a)+10/100 else

If (a>=151) and (a<=150) then b:= ((550*100)+(1100*(a-100)))+10/100 else

If (a>=151) and (a<200) then b:= ((550*100)+(1100*50)+(1470*(a-150)))+10/100 else

If a>=201 then b:= ((550*100)+(1100*50)+(1470*50)+(1600*(a-200)))+10/100;

Writeln (‘So tien ban  phai tra la:’,b:8:2);

Readln;

End.