2)2
=|
ax
-
2
|*
0
bo'lishi kerak.
ax_( a^_z 2 f =
a x _ ax + 2 = l
\ax - 2
1
a) agar
a*>2
bo'lsa,
ax~ax+2=l
tenglama yechimga ega emas.
•
j
b) agar 05-misol. 2 log
2
b
- 3 log*
bx1
+14 log
^^.2
bx = 0
tenglamani yeching.
л
1
Y e c h i s h . * > U,
va £ > 0 > a
8
ar
l°g b—y
desak,
2y2—3y+
b
, ,
.
3 ± V 9 ^ 8
3 ± 1
1 ,
,
,
+
1
=
0
,
y U2
= ------ - ------ = —
;
у ,=
1
,У
2
=
2
>
l°&x b
=
1
.
bundah
=
b,
log*
b
= ^ bundan x
2
=
4b.
2
.
j
d
A
6
-misoI. “
x
”
1
+
tenglamani yeching.
Y e c h i s h .
- lg
2
x
= lg
x
+ a; - lg
2
x
- lg
x -
a =
0
;
a
a
lg
x =
y; 2y 2 - a y - a 2
=
0
,
a
±
\la2 +
8
a2
a ± 3 a
a
y l 2
------------
y ^ a, y 2 -
2>
lg x
=
a, x
=
10
a;
lg x = i- - ^ ,
x =
10
2.
M USTAQIL YECHISH UCHUN MISOLLAR
1-m isol.
21ogx a
+
logaxa + 31oga2x a * 0 ,
a * \ ,
a>Q
te n g la m a n i
*\
1
1
yeching.
Javobi: x i ~
>
x 2
~ a
3
j
^ '
log
3
4 - 2
_ l o g a( 5 - x )
,
n
,
2-mls«l- !оь
7 7
+
2
) _
1
о
8
, ( х +
2
) " '
’
a *
tenglama yechilsin.
Javobi: x = 2
.
3-misol.
“ > "•
a *
1 t«"8lama yechMn.
a 2 ( a + 4)
Javobi: x
= —
x
— — .
a1
+ 4
14-§. Ko‘rsatkichli va logarifmik tenglamalar
sistemasini yechish
\фс + у =5,
I (x +
y ) ■ 2X =
100
1
-misol.
,
4
_ m n tenglamalar sistemasini yeching.
Y e ch ish . Sistemadagi birinchi tenglamaning har ikki tomoni
x
darajaga
ko‘uriladi:
204
\х + у = 5х ,
{(х + у) ■
2х =
100
.
(5х ■
2х
= 100) =» (10х = 102) => (х = 2).
(2 + у = 52) =>
у
= 2 5 - 2 = 23.
Javobi: х = 2, у
= 23.
2
-misoI.
243
<1Ш
а
=
( 2
з х
tenglamalar sistemasini yeching.
Y e c h is h . Sistemadagi ikkinchi tenglamaning har ikki tomoni
у
darajaga
ko‘tariladi:
243,
1024 = |
x
x> = 243,
1024 =
И
243,
102 4-1 j
(243)
x ' = 243,
2
3
= 243,
.10
=>
\x y
= 243,
Jx* = 243,
[2
у =
10
Ь = 5
4 " i
3-misol.
Уу =х,
y 3 = x 2
tenglamalar sistemasini yeching.
Y e c h i s h . Sistemadagi birinchi tenglamaning har ikki tomoni;
i 2
у
darajaga, ikkinchi tenglamani esa
у
darajaga ko'tariladi:
\y 2x = x 2y
у 2 х = у 1У;
у ф
1
boMsa> 2x = 3
y , x = y , x m
1
У ' = л ■
L
bu topilgan qiymatini sistemadagi ikkinchi tcnglamaga qo'yiladi:
205
У
н
3
9
2
^
f з
9
2
л I
2
-
”
1
у - —у
=
0
\=> y 1
4■
H ) - «
9
27
9
^
1
,
2
=
0
,
^3
=
4
.
*
1,2
= 0 >
х з = у >
>'3
=
4
-
'
Г 9 - 5 * + 7 - 2 * ^ =457,
4-misol.
jg
5
x
^4
2
х
+
у
-
-890
tenSlamali sistemani yeching.
Y e c h is h . 5
x=a, 2x+y=b
desak,
9a + 7b = ^
[ 6 a - \ 4 b
(5-t= l)= ( 5x=5')=(x=0);
2*=64=26;
y=
6
.
Javobi:
x=0,
y=
6
.
= 457,
j
a
= 1
■
= -890 ^
= 64,
*v
MUSTAQIL YECHISH UCHUN MISOLLAR
\3x+y+3x +3y
= 7 ,
L [З2^ +
3x+2y
=12.
Javobi:
Xl =
0
, y, =
1
,
x
2
=
1
,
0
-
2 - 9 * +
9
* =
5
* 5-^,
\2-3x-y - 5 y-x =3 - 9 x.
Javobi: x
y = ~ ^ '
( 3 x - y ) * +y
= 4 ,
1
4Sx+y = 7x2 - I 8 x y + 3y2.
r
L .
5
1
Javobi:
x
= —, у = - —.
4
4
4.
\ x - 2 x-y+l+3 y - 2 2x+y
=
2
,
[
2
х -
22
^ + З у -
8
^ =
1
.
Javobi:
x = l,
у = —1.
5.
= 3 2 # 7,
<1
у
=
з
х^
.
[\oga x + ioga у = 2,
5'
[log
6
x - l• log* У = 4.
x, = -2 , л = 4,
Javobi:
x
2
^
I
2
2
2
2
Javobi: x - ab2 У -
■
206
Г
(1
+ log* y )lo g
2
x = 3
Xj =
2
,
Л - 4 »
7‘ [ l o g ^ ( / x 2) - 0 , 5 1 o g ^ / = 2 .
Jwobi:
y2 = - ± .
8
.
x • log
2
1 • logj^
4
=
y j y
(log*
4
-
2),
з
*
Javobi:
v _ o
5
„ _ os
logy 4 • log^j
x
=
2.
x 2
> У
2
•
flog
2
xy + 4
log4(x -
y )
= 5,
jc, =
4
, y, =
2
.
9- 1
/ои 4,; x , = 2 , Л = 4.
TlogyX + lo g ^ J =
2
,
1 0 1
x
2
- д> = 20.
Javobi:
x = 5,
y —
5.
Г к ^ ( х + .у) =
0
t- llo g x
3
, ( y - x ) = l.
3 - V 5
- l + >/5
1L lloe-.C v - x l =
1
.
Javobi: x = - ^ — >
У =
2
2
12
.
lg2 — = 3 lg2 x - l g 2
xi ~ l>
yl = 4,
^
Javobi:
v _ A
v - ?
lg ( y - 3 x ) - l g x lgy
= 0.
2
2
2
{
i&
. W
=
xm
,
|lg (x + y) = lg 40 - lg(x - y).
Javobi.
X
1, у
3.
f
У -2y =516,
14- [log^Cy - x) = 4.
Javobi: x
=
2,
У
=
6
.
15-§. Ko‘rsatkichIi va logarifmik tenglamalarni
graiik usulda yechish
1
-m isol.
2
Jr+l —x-
2X—
1=0
tenglamani grafik usulda yeching.
Y e c h i s h . Tenglamaning chap tom onida berilgan
y=2**1—
x-2*—1=0
funksiyaning grafigini chizish murakkabdir, shuning uchun bu tenglamani
quyidagacha yozib olinadi:
2
x+l-x -
2
jr= l.
207
Bu tenglamaning har ikki tomoni 2**0 ga bo'linadi. Natijada
2—x=2 x
hosil bo'ladi.
y= 2—x
va
y=2 x
funksiyalarning grafiklari (
22
-chizma) koordinata
tekisligida ehizilsa, ularning kesishish nuqtalarining absissalari berilgan
tenglamaning yechimi bo‘ladi.
Javobi: x = —2, x2=
1
,7.
2- misol.
3/og2(x+2)+2x— 3—0
tenglamani grafik usulda yeching.
Y e c h is h . Berilgan tenglamaning
3iog2^x+2)=3—2x
ko'rinishida yozib
olib, tenglikning har ikki tomonida turgan
y=3log3(x+2)
va
y= 3—2x
funk
siyalarning grafiklarini koordinata tekisligida yasaymiz (23-chizma). Bu
graflklar kesishish nuqtasining absissasi berilgan tenglamaning yechimi bo'ladi.
Javobi:
x=0.
3-misol. lg|jc|-x
2
-5 = 0 tenglamani grafik usulda yeching.
Y e c h is h . Berilgan tenglama quyidagicha yozib olamiz:
lgx=x2~5. y=lgx
va
y=x2—
5 funksiyalarini koordinata tekisligida grafiklarini yasaymiz
(24-chizma).
Bu graflklar kesishish nuqtalarining absissasi berilgan tenglamaning
yechimi bo'ladi.
Javobi: x^= 41
, x
2
=- J
5
.
208
4-misol. 2 —
x — 5lg(3
— x) = 0 tenglamani grafik usulda yeching.
Y e c h is h . Berilgan tenglamani
y=2'x
va
y=5lg(3~x)
ko'rinishda yozib,
ularning grafiklarini koordinata tekisligida yasaymiz. Bu grafiklar kesishish
nuqtalarining absissasi berilgan tenglamaning yechimi bo'ladi (25-chizma).
Javobi:
x ,= -l,5 .
x=l , 9.
j
xy + x - 2
=
0
,
5-misol. | x - l o g 2(y +
1
) = о tenSlamalar sistemasini grafik usulda
yeching.
Y e c h is h . Berilgan tenglamalar sistemasi quyidagi ko'rinishda yozib
olinadi:
\xy = 2 - x ,
|lo g 2(y + l) = x =>'
y = .
2
- x
X
y +
1
=
2
*
У = - ~
1,
x
y = 2x - I
У ~ ~ ~
1
va
У=2Х
—1 funksiyalaming grafiklari koordinata tekisligida
chiziladi (26-chizma).
У+'?~х
~
1
\
/У=2х-1
J
-x__ 0
14 - S. Alixonov
209
26-chizma.
Ularning kesishish nuqtalarining absissasi tenglamaning yechimi bo‘ladi.
Javobi: x —
1,
у
= 1.
16-§. Trigonometrik tenglamalar
1
.
sin x = a ten g lam ada |a|< l b o ‘lsa, u
x = { - \) k&Ksma+nk,
k e Z
yechim ga ega bo'ladi. Xususiy holda
a) agar sin x = 0 bo 'lsa, x =
nk, k&
Z;
b) agar sin
x =
1 bo 'lsa, x
= j +2nk, keZ ;
i
d) agar sin x =
-1
b o 'lsa, x = - y
+2nk, keZ;
e) agar sin2x =
a
bo 'lsa, x = ± a rc sin
4a
+
nk, ke Z .
Misol. 2 s i n ^ + x |+
41
= 0
Y e c h is h :
tenglamani yeching.
«V
2 s in
[ + x
]+n/3 = 0
<=> sin I
' n
—
+
X
L
I 4
J
4
2
<=>
К
/ л\к
.
— + x = ( -
1
)* arcsin
4
/
й)
j
+ n k
<=>
)
<=>
t * ( x = ( - l ) k+l- l - l + Kk), k e Z .
3
4
2.
cosx=a tenglamada |a| keZ\
yechimga
ega bo'ladi. Xususiy holda:
7Г
a) agar cos x =
0
bo'lsa, x = —
+як, k e Z
;
b) agar cos x = 1 bo'lsa, x =
Ink, ke
Z;
d) agar cos x =
- 1
bo'lsa,
x = n +2nk, keZ;
e) agar cos2x =
a
bo'lsa, x = ±arccos
4a +nk, keZ.
210
M iso l. c o s |
2 X ~ 2
I-
^ ~ ^ tenglamani yeching.
Y e c h is h .
cos
\ x
2> Do'stlaringiz bilan baham: |