MỘT SỐ BÀI TOÁN VỀ PASSCAL CƠ BẢN


BT 2.29.Giai PT ax+b>0
Program BT229;
Uses crt;
Var a,b,x:real;
Begin
clrscr;
writeln(`Giai BPT dang ax+b>0`);
write(`Nhap vao a,b= `); readln(a,b);
if a=0 then
if b>0 then
writeln(`Pt co vo so nghiem!`)
else
write(`Pt vo nghiem!`);
if a<>0 then
begin
if a>0 then writeln(`Pt co nghien la x> `,-b/a:0:4);
if a<0 then writeln(`Pt co nghien la x< `,-b/a:0:4);
end;
readln
End.
BT 2.20.Giai BPT bac hai : ax^2+bx+c >0
Uses crt;
Var a,b,c,d,x1,x2:real;
Begin clrscr;
writeln(`Giai bpt ax^2+bx+c>0`);
write(`Nhap vao a,b,c:`); readln(a,b,c);
d:=b*b-4*a*c;
if a>0 then
begin
if d<0 then writeln(`BPT co vo so nghien thuc`);
if d=0 then writeln(`BPT co nghien la moi x khac `,-b/(2*a):0:2);
if d>0 then
begin
x1:=(-b-sqrt(d))/(2*a); x2:=(-b+sqrt(d))/(2*a);
writeln(` BPT co nghiem x<`,x1:0:2,` x>`,x2:0:2);
end;
end;
if a<0 then
begin
if d<=0 then writeln(`BPT vo nghien!`);
if d>0 then
begin
x1:=(-b+sqrt(d))/(2*a);
x2:=(-b-sqrt(d))/(2*a);
writeln(`BPT co nghiem la: `,x1:0:2,` end;
end;
if a=0 then
begin
if b=0 then
begin
if c>0 then writeln(`BPT co vo so nghiem x thuoc R`) else writeln(`BPT vo nghiem`);
end;
if b>0 then writeln(`BPT co nghiem x >`,-c/b:0:2);
if b<0 then writeln(`BPT co nghiem x <`,-c/b:0:2);
end;
readln
End.


BT 2.21.Giai PT bac 4: ax^4+bx^2+c =0 (a#0)
Uses crt;
Var a,b,c,d:real;
t1,t2:real;
Begin clrscr;
repeat
writeln(`Giai pttp ax^4+bx^2+c=0 (a#0)`);
write(`nhap he so a,b,c=`); readln(a,b,c);
until a<>0;
d:=b*b-4*a*c;
if d<0 then writeln(`pt vo nghiem`);
if d=0 then
begin
if a*b>0 then writeln(`pt vo nghiem`);
if a*b=0 then writeln(`pt co 1 nghiem x=0`);
if a*b<0 then writeln(`pt co 2 nghiem x1=`,-sqrt(-b/2/a):0:2,`; x2=`,sqrt(-b/2/a):0:2);
end;
if d>0 then
begin
t1:=(-b-sqrt(d))/2/a; t2:=(-b+sqrt(d))/2/a;
if a>0 then
begin
if t2<0 then writeln(`pt vo nghiem`);
if t2=0 then writeln(`pt co 1 nghiem x=0`);
if t2>0 then
begin
if t1<0 then writeln(`pt co 2 nghiem x1=`,-sqrt(t2):0:2,`; x2=`,sqrt(t2):0:2);
if t1=0 then writeln(`pt co 3 nghiem x1=0; x2=`,-sqrt(t2):0