2)

a) y-((1-x)/(1-y))

b)sqrt(x)+abs(y);

3)

Program tinhtienlai;

Uses crt;

Var : a: real;    → Var a: real;

Sokhach: interger;

Begin

Clrscr,    → Clrscr;

Write("nhap a);    →Write ('nhap a: ');  readln (a)

Write('nhap so khach cua chuyen xe: ');

Readin(sokhach);        → Readln (sokhach);

Tienlai- 198000        → Tien lai:=198000;

sokhach-a;            →sokhach:=a;

Writeln('tien lai:', tienlai:10:2');        →Writeln('tien lai: ',tienlai:10:2); 

Readin;          →Readln;

End.

4)

uses crt;

var a,b,c: integer;

begin

clrscr;

write ('nhap a: ');   readln (a);

write ('nhap b: ');   readln (B);

write ('nhap c: ');  readln (c);

writeln ('binh phuong cac so khong am la: ');

if a>=0 then writeln (sqr(a));

if b>=0 then writeln (sqr(b));

if c>=0 then writeln (sqr(c));

readln;

end.