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(1.11)
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1
(1.12)
Misol
.
𝑒
𝑥
− 10𝑥 − 2 = 0
tenglamaning
=0. 01 aniqlikdagi taqribiy ildizi topilsin.
Yechish
. Ma’lumki
𝑓(𝑥) = 𝑒
𝑥
− 10𝑥 − 2
funksiya [-1;0] oraliqda teoremalarning hamma
shartlarini bajaradi. x
[-1;0]
da ikkinchi tartibli hosila
𝑓
′′
(𝑥) = 𝑦𝑒
𝑥
> 0
. Demak f(0)=-1, f(-
1)=8.368 bo`lganligi uchun, f(a)*f(b)<0 shartga asosan f(0)f''(0)<0 bo`lgani uchun {
a
n
} ketma-
ketlik vatarni topish formulasi bilan topiladi.
Berilganlar:
a
=-1,
b
=0,
=0. 01
f(x)= ye
x
-10x-2, f(-1)=e
-1
-10(-1) -2=8. 386, f(0)=e
0
-10*0-2=-1
vatar ildizlarini topish formulasiga asosan:
b
0
=
0
b
1=
b
0
- (
a- b
0
) f(
b
0
)/ (f(
a
)-f(
b
0
))= -0.107
Yaqinlashish sharti
b
1
- b
2
>
bo`lganligi uchun
b
2
yaqinlashishni hisoblaymiz. Buning
uchun
b
1=
-0.107, f(-0.107)=e
-0.107
-10(-0.107)-2 =-0.038 , f(a)=f(-1)=8.386
larga asosan:
b
2
=
b
1
- (
a- b
1
) f(
b
1
)/ (f(
a
)-f(
b
1
)) = 0.111
b
2
- b
1
+
- 0.111+0.107
=0.004<
=0. 01
Demak taqribiy yechim deb t=
b
n
=-0.111 ni olish mumkin.
Vatarlar usuli uchun dastur kodi:
Program Vatar;
Label 1,2,3,4;
Var a,b,x1, x2, eps : real;
Function F (x: real): real; Begin F: = … end;
Function F 1(x: real): real; Begin F 1: = … end;
Function F 2(x: real): real; Begin F 2: = … end;
Begin
writeln(‘a,b=’); readln(a,b);
writeln(‘ aniqlikni kiriting'); readln( eps);
if F1(a)*F2(a)>0 then x1:=a else goto 2;
1: x2:=x1 – F(x1)*(b-x1) /(F(b)-F(x1));
If abs(x2-x1)>eps then begin x1:=x2;goto 1 end else goto 3;
2 : if F1(a)*F2(a)<0 then x1:=b;
4: x2:=x1 – F(x1)*(x1-a) / (F(x1)-F(a));
If abs(x2-x1)>eps then begin x1:=x2;goto 4 end ;
3 : Writeln (‘tenglama yechimi= ‘,x);
End.
Dastur kodida: F - tenglamani o’ng tomoni;
F1 - tenglama o’ng tomonidan
olingan birinchi hosila
F2 - tenglama o’ng tomonidan
olingan ikkinchi hosila
a , b – oraliqni chap va o’ng chegaralari.
Eps – hisoblash aniqligi.
Talabalar mustaqil bajarishlari uchun topshiriqlar
.
1) Tenglama ildizlarini ajratish iteratsion metodi yordamida 0,001 aniqlikda hisoblash.
2) Vatarlar va urinmalar usullari yordamida tenglama taqribiy ildizlarini 0,001
aniqlikda
hisoblash.
3) Tenglamaning taqribiy oraliqlari topib, ularning yaqinlashish tezligini baholash.
1) 𝑎) ln 𝑥 + (𝑥 + 1)
3
= 0;
𝑏)𝑥
3
+ 2𝑥
2
+ 2 = 0.
2) 𝑎) 𝑥 ∗ 2
𝑥
= 1;
𝑏) 𝑥
3
− 3𝑥
2
+ 9𝑥 − 10 = 0.
3) 𝑎) √𝑥 + 1 =
1
𝑥
;
𝑏) 𝑥
3
− 2𝑥 + 2 = 0.
4) 𝑎) 𝑥 − cos 𝑥 = 0;
𝑏) 𝑥
3
+ 3𝑥 − 1 = 0.
5) 𝑎) 3𝑥 + cos 𝑥 + 1 = 0;
𝑏) 𝑥
3
+ 𝑥 − 3 = 0.
6) 𝑎) 𝑥 + ln 𝑥 = 0.5;
𝑏) 𝑥
3
+ 0.4𝑥
2
+ 0.6𝑥 − 1.6 = 0.
7) 𝑎) 2 − 𝑥 = ln 𝑥 ;
𝑏) 𝑥
3
− 0.2𝑥
2
+ 0.4𝑥 − 1.4 = 0.
8) 𝑎) (𝑥 − 1)
2
=
1
2
𝑒
𝑥
;
𝑏) 𝑥
3
− 0.1𝑥
2
+ 0.4𝑥 + 2 = 0.
9) 𝑎) (2 − 𝑥)𝑒
𝑥
= 0.5;
𝑏) 𝑥
3
+ 3𝑥
2
+ 12𝑥 + 3 = 0.
10) 𝑎) 2.2𝑥 − 2
𝑥
= 0;
𝑏) 𝑥
3
− 0.2𝑥
2
+ 0.5𝑥 − 1 = 0.
11) 𝑎) 𝑥
2
+ 4 sin 𝑥 = 0;
𝑏) 𝑥
3
− 0.1𝑥
2
+ 0.4𝑥 + 1.2 = 0.
12) 𝑎) 2𝑥 − lg 𝑥 = 7;
𝑏) 𝑥
3
− 3𝑥
2
+ 6𝑥 − 5 = 0.