https://www.youtube.com/watch?v=wmfG8TpDMNs

uses crt;
type ht=record
ho:string[15];
dem:string[10];
ten:string[10];
end;
var a:array[1..100] of ht;
stmp:ht;
i,j,n,tmp:integer;
s1,s2:string;
begin
clrscr;
write('So hs < 50! so hs=');readln(n);
for i:=1 to n do
begin
write('Ho hs ',i,':');readln(a[i].ho);
write('dem hs ',i,':');readln(a[i].dem);
write('Ten hs ',i,':');readln(a[i].ten);
end;

for i:=1 to n do
for j:=i+1 to n do
begin
if a[i].ten>a[j].ten then
begin
stmp:=a[i];
a[i]:=a[j];
a[j]:=stmp;
end;
if a[i].ten=a[j].ten then
if a[i].dem>a[j].dem then
begin
stmp:=a[i];
a[i]:=a[j];
a[j]:=stmp;
end
else if a[i].dem=a[j].dem then
if a[i].ho>a[j].ho then
begin
stmp:=a[i];
a[i]:=a[j];
a[j]:=stmp;
end;

end;
for i:=1 to n do
begin
writeln('Hs ',i,':',a[i].ho,' ',a[i].dem,' ',a[i].ten);
end;
readln;
end.

a) 3x(12x-4)-9x(4x-3)=30

\(\Leftrightarrow\)3x(12x-4)-3.3x(4x-3)=30

\(\Leftrightarrow\)3x(12x-4-12x+9)=30

\(\Leftrightarrow\)3x.5=30

\(\Leftrightarrow\)3x=7

\(\Leftrightarrow\)x=\(\dfrac{7}{3}\)

b)x(5-2x)+2x(x-1)=15

\(\Leftrightarrow\)5x-2x²+2x²-2x=15

\(\Leftrightarrow\)3x=15

\(\Leftrightarrow\)x=5

a) 37,5.6,5-7,5.3,4-6,6.7,5+3,5.37,5

=(37,5.6,5+3,5.37,5)-(7,5.3,4+6,6.7,5)

=37,5.(6,5+3,5)-7,5.(3,4+6,6)

=37,5.10-7,5.10

=375-75

=300

b) 45²+40²-15²+80.45

=45²+2.40.45+40²-15²

=(45+40)²-15²

=(45+40-15).(45+40+15)

= 70.100

=7000

1 và 3

x⁴-4x²-6x+12

=(x⁴-4x²)-(6x-12)

=x²(x²-4)-6(x-2)

=x²(x-2)(x+2)-6(x-2)

=(x-2)[x².(x+2)-6]

a)43,5.5,5-3,5.2,7+43,5.4,5-3,5.7.3

=(43,5.5,5+43,5.4,5)+(-3,5.2,7-3,5.7,3)

=43,5.(5,5+4,5)-3,5.(2,7+7,3)

=43,5.10-3,5.10

=435-35

=400

b)35²+40²-25²+40.70

=(35²-25²)+40²+40.70

=(35-25).(35+25)+40²+40.70

=10.60+40²+40.70

=600+1600+2800

=2200+2800

=5000

const
fi='botri.inp';
fo='botri.out';
var
f:text;
i,n,t:integer;
procedure inp;
begin
assign(f,fi);
reset(f);
read(F,n);
closE(F);
end;
procedure out;
begin
assign(f,fo);
rewrite(F);
t:=1;
for i:=n-1 downto 1 do
t:=t*i;
t:=t*2;
write(f,t);
closE(F);
end;
BEGIN
INP;
OUT;
END.

const
fi='botri.inp';
fo='botri.out';
var
f:text;
i,n,t:integer;
procedure inp;
begin
assign(f,fi);
reset(f);
read(F,n);
closE(F);
end;
procedure out;
begin
assign(f,fo);
rewrite(F);
t:=1;
for i:=n-1 downto 1 do
t:=t*i;
t:=t*2;
write(f,t);
closE(F);
end;
BEGIN
INP;
OUT;
END.