Первая:
Var X:real;
Begin
Write('X = ');ReadLn(X);
if X<6 then WriteLn(X*X);<br>if (X>=-6)and(X<6) then WriteLn(Abs(X)+4);<br>if X>=6 then WriteLn(X*(X+1))
End.
Вторая:
Var A,B:real;
Begin
Write('A = ');ReadLn(A);
Write('B = ');ReadLn(B);
if ((A>=0)and(A<=15))or((B>=0)and(B<=15)) then WriteLn(A*A+B*B)<br>else WriteLn((A+B)/2)
End.
Третья:
Var A,B,C,D:real;
Begin
Write('A = ');ReadLn(A);
Write('B = ');ReadLn(B);
Write('C = ');ReadLn(C);
D:=B*B-4*A*C;
if D>=0 then
Begin
WriteLn('X1 = ',(-B+sqrt(D))/(2*A));
WriteLn('X2 = ',(-B-sqrt(D))/(2*A));
End
else WriteLn('Корней нет')
End.