Первое

Begin
  var y, a, x, b: double;

  write('Vvedite cherez probel a, b, x: ');
  readln(a, b, x);

  if a < 2.3 then
    y := a * x * x - (a * sin(x) - b * cos(x))/(sin(x) - b + 5.2)
  else
    if a > 5.3 then
      y := sin(a * x) - sqrt(x + a + b)
    else
      y := b * tan(x) + exp(5 + x) * ln(a + b);

  writeln('x=',x,' a=',a,' b=',b,' y=',y);
End.