var
a,b,c:integer;
begin
a:=−21;
b:=abs(a);
writeln('abs(−21)=',b);
c:=sqr(b);
writeln('sqr(b)=',c);
c:=sqr(b+b);
writeln('sqr(b+b)=',c);
end.

При запуске программы вывод на экран:

Const e=0.001;
var x,xn,h,an,s,f,y:real; n,k,i:integer;
begin
n:=10;
h:=(1-0.1)/(n-1);
x:=0.1-h;
for i:=1 to n do
 begin
 x:=x+h; an:=1;
 xn:=1; f:=1;
 k:=0;  s:=1;
 while an>e do
  begin
  xn:=xn*x*x;
  k:=k+1;
  f:=f*k;
  an:=(2*k+1)*xn/f;
  s:=s+an;
  end;
 y:=(1+2*x*x)*exp(x*x);
 writeln('x = ',x:4:1,'  s = ',s:6:4,'  y = ',y:6:4);
 end;
end.

Результат:
x = 0.1  s = 1.0303  y = 1.0303
x = 0.2  s = 1.1241  y = 1.1241
x = 0.3  s = 1.2911  y = 1.2911
x = 0.4  s = 1.5490  y = 1.5490
x = 0.5  s = 1.9260  y = 1.9260
x = 0.6  s = 2.4653  y = 2.4653
x = 0.7  s = 3.2320  y = 3.2320
x = 0.8  s = 4.3240  y = 4.3240
x = 0.9  s = 5.8894  y = 5.8895
x = 1.0  s = 8.1548  y = 8.1548

1)
var a:string;
    i, o: Integer;
    p: Real;
begin
     readln(o);
     a := inttostr(o);
     for i := 1 to length(a) do
        p := p + strtoint(a[i]);
     if (sqr(o) = p*p*p) then writeln('true')
        else writeln('false');
end.

2)
var a:string;
    i, o, p: Integer;
begin
     readln(o);
     a := inttostr(o);
     for i := 1 to length(a) do
        p := p + strtoint(a[i]);
     if (p mod 3 = 0) then writeln('true')
        else writeln('false');
end.

3)
var a, b, c: real;
begin
     readln(a, b, c);
     if ((a = b) and (b = c)) then writeln('true')
        else writeln('false');
end.

Всё проверено, удачи:)