For SB 1b

program sb1b;
USES CRT;
var x, a, b, h, y : real;
begin
    clrscr;
    write('Enter interval from ');
    readln(a);
    write('to ');
    readln(b);
    if a > b then
        begin
            writeln('Error! ', a:5:5, ' > ', b:5:5);
            readln;
            exit;
        end
    else
        if a = b then
            begin
                writeln('Error! ', a:5:5, ' = ', b:5:5);
                readln;
                exit;
            end;
    write('Enter step: ');
    readln(h);
    if h <= 0 then
        begin
            writeln('Error! Step must be positive!');
            readln;
            exit;
        end;
    x := a;
    while x <= b do
        begin
            if (sqr(x) - 2 * x) < 0 then
                writeln('y = a + b')
            else
                if ((sqr(x) - 2 * x) >= 0) and ((sqr(x) - 2 * x) < 10) then
                    writeln('y = a - b')
                else
                    writeln('y = a * b');
            x := x + h;
        end;
    readln;
end.