Giai he I bkng phLrong phap the... MOT SO HE PHl/dNG TRINH DAI SO KHAC.
Trang 1I DA
5, c
6 h
(x) = Oc^x =
- 5 + 0
0 +
+
g(x) = 4x2
- 0 +
^_ h(x)
g(x) + 0
+ 0
X
e '3
u (4;
+oo)
f(n) =
0 vdi
X =
1,
X = -
2
, x = 4
X
j =
- , X2
= 2
fix) >
0 (f(x) cun
g da
u vd
i 2) vdi x < - hoac x
> 2 Va
I 2_
2;
+c o).
Bieu die
n ta
p
nghiem tren tru
e so' (pha
»
« f
p nghie
m T = (-3
-V Tn
h CS
n
Trang 219. Giai he bat phifofng trinh va bieu dien tap nghiem tren true so :
x' + x - 6 > 0 (1)
x ' - 5 x + 4 < 0 (2) - 3
(I)
( 2 ) i ( i ) i
Tap nghiem cua he (I) : T = T i n T2 = [2; 4) ^
20 Trong moi trirdng hop, t i m cac gia t r i tham so m de :
a) PhtfOng trinh : (3m + l)x^ - (3m + l)x + m + 4 = 0 (1) c6 hai nghiem
m2 = -— CO gia t r i diiong (trai dau vdi -3) vdi -15 < m < - —
3 3
b) Neu m = 4 phirong trinh (2) c6 dang : 5x + 7 = 0 c6 mot nghiem
f m ^ 4 PhUOng trinh (2) v6 nghiem neu \
Trang 3= 0 <=>
i
= 1,
n t
hi ph
ai c
6
3m-2
p nghie
m cu
a (1) t
g ho
p diid
i day, ha
y tim cac gi
a t
ri cu
a tha
h : (m
- l)x
^ 2mx +
m +
5 =
0 (1)
b) phiron
g trin
h : 4x^ - (3m + l)x
- m
- 2 = 0
; 2)
CH
I DA
N
a) Ne
u m = 1, phtTon
g trin
h (1) c
6 nghie
m du
y nha
t x = 3
g (0
; 1)
Neu m ^ 1,
phirong trin
h (1) l
a phiion
g trin
h ba
c hai A
g trin
h
fix) = (m
- l)x
^ 2mx +
rin
h (2) c
u m
lay
cdc
gia tr
i tho
a man cac die
u kie
n sa
u :
A = (3m + + 16(m
+ 2) >
0
af (-1) = 4[4 + (3m + 1) -
m 2] >
0
af (2) = 4[16 - 2(3m
+ 1) - m
- 2] >
0
, S 3m
+ l -
-1 < — = <
9m' + 2m + 3
3 >
0
2m + 3 > 0
23.
Tim cac gi
a t
ri cu
a tha
m s
o m
de phiron
g trin
h
(m
- 2)x
^ 2mx + 2m
- 3 = 0 (1)
Trang 4• Neu 2 - m < 0 o m > 2 thi (1) c6 hai nghiem thoa man xi < 2 < X2
• Neu 2 - m = 0 <=> m = 2 t h i (1) c6 cac nghiem 1 = x i < X2 = 2
• Neu 2 - m > 0 o m < 2 t a xet them biet thufc
C H I D A N
Tam thu-c ve trai (1) la : fix) = x^ - (m + l)x + 2(m - 1) = 0
o X = m - 1 hoac x = 2
• Neu m - 1 < 2 o m < 3 thi (1) c6 tap nghiem Tj = [m - 1; 2]
• Neu m - 1 > 2 m > 3 t h i nghiem cua (1) la : Ti = [2; m - 1]
• Neu m = 3 thi Ti = 121
Xet tam thufc ve trai cua bat phtTcfng trinh (2) :
g(x) = x^ - (m + 2)x + 3(m - 1) c6 cac nghiem x = m - l v a x = 3
• Neu m < 4 tap nghiem cua (2) la : T2 = (-00; m - 1] u [3; +co)
• Neu m > 4 tap nghiem cua (2) la : T2 = (-co; 3] u [m - 1; +00)
• Neu m = 4 : T2 = {3}
Tap nghiem T = T i n T2 cua he (I) nhif sau :
+ Neu m < 3 t h i (I) c6 nghiem chung duy nhat x = m - 1
Trang 5T PH UC IN
G TR IN
H
CHlfA
D AU G IA T
RI TU YE
T DO
I
KIEN TH
L fC
1 Phx:ifofn
g t ri nh chtfa
d au gia t
ri tu y^
t do
i
La phucfn
g trin
u gi
a
tri tuyet do'i
i gia
i phiron
g trinh
l
a diT a
tre
n din
h nghi
a
a ne
u a > 0
-a neu
diTOng
Dac bie
t : | A(x) | = | B(x) i
o (A(x)f = (B(x)f'
2 Ba
t phu:cifn
g t ri nh chtfa d au gia t
ri tu y$
t do
i
Cac phtron
g trin
-g(x) hoS
c fix) >
h cha
t cij
a gi
a tr
1
3 -a
h : (1) 7 2x = 4 - X + a
CH
I DA
N
a) The
o din
X >
-4
-(x + 4) vdi
X <
-4
(1) « (A)
(B)
Jlx + 4)-2x = 7
X
>
-4
-(x + 4) - 2x =
7
X <
u Th
g Hi^
u Nguyln VFnh CJn
Trang 6-(A) o - x + 4 = 7 _ r - 3 x - 4 = 7 <=>x = -3; (B) < = > v 6 nghiem
Vay phuong trinh (1) c6 nghiem duy nhat x = - 3
b) De CO bieu thufc khong chufa gia t r i tuyet doi ttrcrng duong ta lap bang sau
Trang 7Phifdng trin
h (1) c
Vs _ -
1 +
X -0 0
-4 -2
-2{x^ +
6x + 8 ) 0 2(x^ +
Gx +
8 2(x^ + 6x + g 2(x^ +
x^
1 0 -
^ + 12x + 1
5 =
30 -x 2- 12 x- 17
=3
0 (c)
(d) (e)
Ng hi
em
(c) o _^
17 =
30
T Cr cac phiron
X
= 1
x
3
c) x2-x = 3 x-1
CH
I DA
N
11 b)
X =
1 va
X = —
<2 (1) b
) i'2x+*l
| >
3' (2)
CH
I DA
N
a) (1)
< ;>
-2 < 3
x - 1 < 2 <=>
-1 <
3x < 3
« — < X
N
(1) o-(3x-3)
<(
x2-2x-3)
<3x-
x' 5x <
0 0
< X <
5
< => 2
< X <
u u Nguyin
VT
n h CJ
n
Trang 8§5 PHlIOfNG TRINH, BAT PHlJOfNG TRINH CHlfA CAN THtJC
KIEN THCfC
PhiTofng phap chung de giai phtTOng t r i n h c6 bieu thufc chufa a n nam
diTdi dau can la nang l e n luy thCra bieu thufc cua phifcfng t r i n h v d i cac dieu k i e n d i k e m de c6 diroc phucfng t r i n h khong con chufa a n trong dau can Cung c6 the dSt a n phu de d a n den cac phifcfng t r i n h , he
phuong t r i n h don gian va de giai h o n M o t v a i dang phifOng t r i n h
chufa can thiJc dan gian la :
B a t phu!ofng t r i n h chufa c a n thiJc
Dang CO b a n cua bat phiTOng t r i n h chura can bac hai
f (x) > 0 g(x) < 0 g(x) > 0 •
de giam dan cac dau can thufc, dan dan dtTa t d i bat phifong t r i n h , he
bat phufong t r i n h khong chuTa cSn thufc Cung c6 the dat cac a n phu
hoSc bien luan cac ve cua bat phuong t r i n h de t i m nghiem
Trang 99 =
0
b) (2)o V3
x +
= 3
+ V x
-3c^
9
x
-3
>0 x>
If o
x^ llx + 28 = 0 <^
-x =
4
x = 7'
- 3
x +
3 +
V x'
N
a) Nha
n xet: 6x
^ - 12
x +
7 = 6(x - 1)^ +
Dat t = Vex '
-12x +
7 vd
i t
> 0, t
a c
6 :
x^ 2x =
-va phiran
g trin
h (1) da
n de
n
t' + t
t = -
1 (loai)
t =
7
6x' 12x +
7 = t'
b) Nha
n xe
t : x^ - 3x +
G
Dat t = x
^
3x +
3, ta
CO :
(2)
Vt + V tT 3
= 9 +1' -
et
0<
t<
3 ot
=
1
(2
)o Vx
'
3x + 3 = lc:>
2 + V4 -
x = x' - 6x +
11 (11 )
CH
I DA
N
Ve pha
i (1 )
la : x^ - 6x +
11
= (
x 3)^ +
= l
.V x
l')[(
2) + (4-x)]
x-=2
40
GH
TS V
U Th§
' Hu
u Nguyen VTn
-h Ca
n
Trang 11> m
<=
>m-x
>0o
x =
m
x^
-m'=
(m-x)'
Ket luan :
Vdi m > 0, phuon
g trin
h (1) luo
n c
6 mo
t nghie
m x = m
h ta thay dieu kie
n xa
c din
h m
> 0
2>
m-0
x' 2mx +
1 = (m
- 2)2
(2)
o Vx
^ 2mx + 1
trin
Neu
m, ne
u m
> 2
phiTofng tr
m s
o m phifcfng
trin
h c
6 nghiem
V3
+ X + V6
- X - V
(3 +
x)(6 x)
= m
(1)
CH
I DA
N
Cdch 1 :
DKX
- x) +
=> (
u + v)^ -
2(u
+ v) +
m (loa
i u + v
= 1
- Vl 0- 2m )
^ ju
^ + = 9
Ta thay
u +
v =
Vu^ + + 2u
-u +
V =
l.u + l.v < V(l' + l')(u' +v') -
3V2
Vay3
<u + v
<3V2 ^3<
6V2 —
9 < m : Ydi Ket luan < 3
phiTcfng trin
h (1) c
6 nghiem
Cdch 2 :
t cu
a t tre
V6
x V3
+ X ^
3 = 0 =^ ,— , — —, = o
X =
Min t(x) = min-|t(-3); t
- ; t(6)^
= min{3
; 3^2
; 3} =
42 ^ TS V
Q ThS ' H^
u Nguygn VTn
-h C?
n
Trang 1215u' + 4u' - 32u + 40 = 0
Hoc va 6n luy?n theo CTBT m6n ToSn THPT S 4 3
Trang 13<=> i
V =
2u
8-ru = -
^ X =
(u + 2)(15u' -
26u + 20 ) =
0
b) DK XD : -
2 <
X
< 2 D
at u
= V 2
+ x , v
= V 2
- x t
a c
6 h
e :
(I) + =
4
3u 6v + 4 uv = 3v
- 2vf
3u -6
v = 4 v' -4 uv
+ u
'(
*)
u 2
-v =
0
u 2
-v =
3
(D
o + =
4
u 2
-v =
3
(A ) (B)
He (A
) C O
gh ie
m v^
= —
o 2 -x = — =>x =
He (B ) v
6 n gh ie
m
Va
y phucfn
g t rin
h (2 )
c6 ng hie
>/^7T
- V
x + 1
= 4
(1)
(Trich de thi tuyen
sinh DH khoi D
- 2005)
b) V2 x
- l +x '- 3x + l = 0 (2)
(Trich de thi tuyen
sinh DH khoi D
- 2006)
CH
I DA
mh phiTofng
ha
i v
e
(1) 2Vx +
2 + 2Vx + 1
17 +
x + 8Vx +
X =
3
Cdch 2 : N
ha
n x
et x
+ 2 + 2V
x +
1 = (1 +
+ 1
-4 [V
b) (2 )<
» V2 x- 1
= x^
> 0
2x -1 =: (-x ' + 3x -
-x
^ +
3x -1
> 0
x' -6x=
' + l lx '- 8x + 2
= 0
44 S5
TS V
u Thg ' Hu
u Nguygn VTn
-h Ca
n
Trang 143 - V 5 3 + V5
< X <
c:>x = l v x = 2 - V 2
2 2 ( x - l ) ' ( x ' - 4 x + 2) = 0
41. T i m m de phifofng t r i n h sau c6 h a i nghiem thiTc phan biet
N h a n xet phu'cfng t r i n h (*) c6 he so cua x^ va he so tu do t r a i dau nen
(*) t r a i dau, suy r a (*) phai c6 m o t nghiem thuoc nUa khoang
Dieu nay xay ra k h i m thoa m a n cac dieu k i e n sau :
t r e n t a c6 the viet n h u sau :
(A) va he ( B ) : T = (-oo; - 2 ] u [14; +oo)
43. Giai cac bat phiJOng t r i n h :
i) V l 1 - X - Vx - 1 < 2 (1) b) Vx + 3 - V7 - X > V2x - 8
Trang 15I DA
x
<2 + Vx-l«
ll-x
<[
2 +Vx-
4
o
-12x + 20<
4
(x
- 1)
C
:>2
< X <
x-8
>0
o 4
<x
<7
'4 <
X < 7
X
+ 3
> (7
- x) +
(2x
8) +
2V7-xV2
cua (2) l
at phiron
g trin
h : V3x^ + 5x
+ 7
- VSx
^ + 5x + 2 > 1 (1)
CH ID
AN
o — x > c 1 hoa - x < > 0 + 2 5x ^ + : 3x DK Da
t
t = 3x^ + 5x
+ 2
(1) tr
d thanh : V
t +
5 >/t >
t + 5
>l+t
+ 2V
t
4 < X <
7
-x' + llx-30<
- 2 < 0
3
-2
< X < —
3
46 ^
TS V
u The '
Hifii
Nguygn Vin
h CS
n
Trang 1645. Giai bat phuong t r i n h : ^^^^^^^ + V^T^ > 4=^ ( D
He (A) CO nghiem : x < 5, he (B) c6 nghiem 10 - ^/34 < x < 5
Tap nghiem cua (1) la : x > 10 - V34
46. Giai bat phifofng t r i n h :
Ta CO X = 0 la mot nghiem cua (2)
Xet X > 0, chia hai ve cho \fx t h i diroc : V x + + J x + — - 4 > 3
4
HQC V§ 6n luy§n theo CTDT mfln Jo&n THPT El 47
Trang 171 H$ phi^ofng
tr in
h b ac n ha
t h
ai an , b
6 dang:
aj X
+ b iy
^C j
(1)
a2
X + b 2y = C 2
(2)
(I)
Ki hie
u D =
b2
Ci
b,
C2 b2
ai C:
a2 C2
= ai b2
- a2 bi
goi l
a din
- C2
bi
- ai C2
- a2
Ci
Quy tdc Crame.
Giai h
e phifcfn
g trin
h ba
c nhat
t (xo
; yo) xa
D., _ y = yo
Cho h
e phiion
g trinh:
(I)
- Ne
u D
= D
x = Dy
= 0 he
(I)
c6 v6 so nghiem
x + biy
b) Gidi
he phiiang trinh bac
nhat hai
an bdng phuang phdp
do thi
ai X
+ bj
y =
c, (1)
[a aX +
\y
= C 2
(2)
Tren cung mo
h (1) v
a duTcfn
g thang
(d2) c
6 phtfcfn
g trin
h (2)
a gia
o die
m (di) v
- Ne
u (di) v
6 nghie
m du
y nhat
6 nghiem
e (I) c
6 v
6 s
o nghiem
Toa do moi die
m cu
a (di) (ha
y (d2)
) l
a mo
t nghiem
h sau:
a) (I) 2x - 3y = -
4
3x +
y =
5 b)
(II)
+ 5
y -3
48
S TS V
u Thg ' Hi;u
- Nguye
n Vin
h CS
n
Trang 18b) Dieu k i e n xac dinh ox ^ 2 DSt X =
9 m + 3 -5m^ - 3m + 2 •
Hoc 6n luy§n theo CTDT mfln Jo&n THPT 0 49
Trang 19a) (I ) x +
3x 2y +
z = 6 (3)
CHI DA
N a) DKXD
: x ^ -2, y
^ -1 D
M X =
29
x + 2
Y =
y + 1 thi (I
a tin
h difd
c X = — , Y = —
b) (II ) J2
i -2 dem con
g va
o phiTcfn
g trin
h (2) La
) h (2' g trin n phiTOn c nha p tu Lai tie
) cu
a (II)
i vdf
i -8 , con
^1
2
3 10^
10 -8 -8 -24;
u The ' HiA
i - Nguye
n Vin
h C5
n
Trang 20Giai he (I) bkng phLrong phap the
b) He phiiong trinh dot xiing loqi I
La he phufdng t r m h co dang <
lg(x,y) = 0 (2) Trong do f(x, y) va g(x, y) la cac bleu thufc doi xufng doi v6i cac bien x, y
Cdch giai: Dat an so phu S = x + y, P = xy
Dieu kien can va du de he c6 nghiem la - 4P > 0
rf(x,y) = 0 (1)
c) He phiiong trinh doi xiing loai H: (II)
Cdch giai: Di/a viec giai he (II) ve giai he: (F)
Trong do m6i phuong t r i n h cua he la mot dSng thiJc cua cac da thufc dang cap cung bac
Cdch giai: Giai he ( I I I ) v d i x = 0 hoSc vdi y = 0
Vdi x ;t 0 dat y = kx hoSc v6x y 0 dat x = ky r o i khuf an de doi ve
giai phirong t r i n h mot an
1 3 - 5 y \ + 3y' - m = 0 o 52y^ - 130y + 169 - 9m = 0 (2')
Biet thufc cua (2'): A' = 65^ - 52(169 - 9m) = 468m - 4563
Trang 2139 5
9 = — p y m ke 6 nghie ) c 0, (2' ' = , A — m = Neu => x
i (2') c
6 ha
i nghie
m
yi 2
e (I)
51.
Gia
i h
e phiTOn
g trin
h
CH
I DA
N
xy +
X
+ y = 1
1
xV + xy
^ =
30
(Trich de thi vdo
DHGTVT 2000)
-Dat
X
+ y = S, x
y =
P, t
a c6: fS + P = 1
a nghie
m cu
a phtron
g trinh: - IIX + 3
y =
6 hoac
X
+ y = 6
; 2), (1; 5), (5
3x = x^ +
2
(Trich de thi tuyen
sinh DH khoi B
- 2003)
CH
I DA
N
TCr ca
c phifdn
g trin
h cu
a (I) su
y r
a x > 0, y > 0
'3xV = y' +
2
^ 3y'
x = x^ +
2
(I)«
3xV
= y' +
2
(x y)(3xy +
x + y) =
-3x
V = y^ +
2
3xy
+ X
+ y = 0
(A) (B)
y =
X
TCr die
u kie
n x > 0, y > 0 Su
y ra: 3x
6 nghie
m du
y nha
t x = y = 1
52
a TS Vi
j Thg ' H
U u Ng
-u ye
n Vin
h CS
n
Trang 2253 Giai v a b i e n l u a n theo t h a m so a he phtfcfng t r i n h (I)
Trang 231-—
xy v6
n gh ie
m
X
+ y = 0
y = -V2
X =
V2
-; y = V2
x = l , y -
1
x =
-l, y = -l '
a) (I ) b)
(I I) x^
-y
^=
7 (1 )
xy (x -y ) =
2 (2 )
55 Gi
ai he p hi/
dn
g tr in h:
3x '+
2x
y + y^
= 11 (1)
x' + 2 xy + 3 y' = 17 (2)
CH
I DA
N
a) Ve t ra
i cu
a (1 ) v
a (2 ) h
e ( I) la cac da thufc da ng c ap bac
g vdf
i x = 0 hoac y = 0 h
e ( I) v6 n gh ie
m
x'(
3 + 2
k +
') = l
l (1'
Ch ia ve vdfi ve (1") va (2') th
l + 2
k + 3 k' ) = 17 ( 2')
3k ' + 2
k +
1 1
7 4k2 - 3k
- 1
0 =
0 ^
k = -
- hoa
c k = 2
t
a dtfo
c y = — x, p hif on
g t ri nh (1) tr
d t ha
1 1
<=
> X
Th ay
k =
2 t
a s
e t im dtTcfc x = ±
1, y = ±
y h
e ( I) c
6 4 n gh ie
m l a:
3 ' -4V3 5V
( 2 )
b) Nh an x et
Sn
g x = 0 k ho ng n gh ie
m dii ng h
e ( II )
x t
hi he ( II ) t rd
ha
nh
x' (l -t
=' ) =
7 (1' )
x' t(
t) =
2 (2 ')
1
(I
D
1 _ f 3
n
^ =
- =:
> 2 t' - 5
t +
2 =
=> t = 2 hoac t = -
2
La
m tu on
g tii
cau a) ta dtroc h
e ( II ) c
6 h
ai ng hi em l
a ( -1
; 2) v
-a (
2; 1)
56 Ch
o h
e phucfn
g tr in
h vdi
t ha
m s
o m
x' y', + m (x + y ) =
X
- y + m (1)
x^ +
' + x
y =
3 (2 )
V(Ji gi
a t
ri na
o c ua
m t
hi he ( I) c
6 d un
g 2 n gh ie
m
(I)
54 EJ
TS V
u Th
e H
u u Nguyen
Vinh C$n
Trang 24[3x' + 3ax + a ' - 3 = 0(2') PhucJng trinh (2') v6 nghiem neu A = 9a^ - 12(a^ - 3) < 0
o a < -2V3 hoac a > 2>/3
MOT SO HE PHl/dNG TRINH DAI SO KHAC
Trang 25(A)o (B)<=>
+ y = 0
xy =
X
+ y =
3
xy =
CH
I DA
^ = 2x + 9 (1)
x^ + 2xy = 6
x +
6 (2)
(Trich de thi tuyen
sinh DH khoi B
- 2008)
(D
o (x^ + xy)^
= 2
x +
9
xy = 3x + 3 x'
12x^
+ 48
x + 64) =
0 o x(x + 4)
^ =
Vi x = 0 khong
nghiem dung (2'
Vay
he (I) c
6 nghie
m du
y nha
t -4;
17 4
j
a) (I)
59.
Giai h
e phtfon
g trinh: '
xy +
X +
1 = 7y (1)
xY
+ x
y +
1 = 13y2 (2)
(Trich de thi tuyen
sinh DH khoi B
- 2009)
x(x +
y + 1) -
3 =
0 (1)
b) (II) (x + y )^
-4 + l = 0 (2)
(Trich de thi tuyen
sinh DH khoi D
- 2009)
CH
I DA
N
a) Vd
i y = 0 khong
nghiem dung h
e (I), d
7 y y
X —h -
y y x^
+ ^ = 1
+-3
56 Ea
15 V
u Thg '
H\ju - Nguyi
n Vin
h CS
n
Trang 26Dat a n phu x + — = u, — = v ta diroc:
• y y
u + V = 7
u ^ - v = 13
u + V = 7 + u - 20 = 0
1 la cac nghiem cua he (I),
b) Dieu k i e n xac dinh x ;t 0, he ( I I ) c6 the viet t h a n h x(x + y) + X = 3
x^(x + y)^ +X ' = 5
Dat u = x(x + y) t a ducJc he
u + X = 3 u^ + x^ = 5 o
u + X = 3 (u + x)^ - 2xu = 5 0 -
(Trich de thi tuyen sink DH khoi A - 2011)
C H I D A N
TCr phi/0ng t r i n h (2) cua he (I) ta c6:
(2)c^ xyix^ + y^) + 2 = x^ + y^ + 2xy o (x^ + y^ - 2)(xy - 1) = 0
TCr do he (I) tiicfng dirong v d i hcfp cua hai he phiTcfng t r i n h
+ Thay 2 = x^ + y^ vao (1) ta diTcfcSxV - 4xy^ + 3y^ - (x^ + y^)(x + y) = 0
2y^ - 5xy2 + 4 x V - x^ = 0 (*)
H Q C vk 6n luy$n theo CTDT m6n Toan THPT 57
Trang 27i X
=
0, y = 0
t y = k
x t
hi d\iac
x^(2k^ 5k^ + 4k
- 1) =
0
=> k = — hoSc k
= 1 2
- Vd
i k = 1 ta tim difcfc ca
c nghie
m cu
a h
e (B) trung vdi ca
c nghie
m cu
a
he (A)
XTA- 1
1 ^ ^ 2V10 ^
2 •5
lj 2V lO Viol
;-f 2VI O
(I) x=
3x'-9x + 2
^-2 =
y 3
+ 3y'-9
y (1)
2 2
1 - +y x x+
y=
— (2)
(Trich de thi tuyen
sinh DH khoi A
- 2012)
CH
I DA
N Xet phuon
g trin
h (1) cu
a h
e t
a c6:
(D o (x -
If
12(x 1) = (y +
if
12(y + 1)
(x 1)^ - 12(x - 1) = (y +
- 12(
y + 1)
(DoCD {
\
X -
1 + — y
^ 2
A2
= 1 (2-)
TCf (2') su
y ra: -
1 3 a — — v l< x- < hay — <
m s
o fTt) = t^
- 12
t tre
n doa
n
f (t) = 3t^ -
12 <
0 Vt
e
[-2; 2]
Vay ha
m s
o fit) = t^
- 12
t nghic
h bie
n tr
en
ta th
ay
3 3
2' 2
Vi vay
a c6:
(x
- If -
12(
x- l) = (y + 1)'
- 12{
y +
)ox-
a h
e (D ta difoc
= 1
0 y = -
— ho&
c y = - — 2 2 •
58 TS V
u Th
g Hu
u Nguyin Vin
-h C$
n