35
TRUNG TÂM D Y THÊM
Câu
1
LÊ H NG PHONG
=
(C)
: D = R\{ 1}.
:
y=2
a
*
*
lim
(C).
,
lim
; lim
* y' =
(
* y' > 0,
*
x
y'
0.25
.
x= 1
.
0.25
)
x D
:
1
+
2
*
; 0); ( 2; 5); (
: (0; 1); (
; )
:
6
5
4
3
2
1
-5 -4 -3 -2 -1
-1
-2
b
y
0.5
x
1
2
3
(C)
(d)
0.25
+
2
y
*
.
( 1; 4).
0.75
(C)
(x0; y0)
(d): y y0 = y'(x0)(x x0)
(d): y =
(
)
(d) qua A
3 + 2x0
(
(
)
(
)
1 = 4x0 + 4
(d): y =
(
2
0.25
2x0 = 8
)
=
.
: I=
(
)
I=
x0 = 4
( )=
y0 = 3; y'( 4) =
0.25
1.0
0.25
.
* I1 =
* I2 =
0.25
.
)
=e
1.
0.25
:
u=x
v' = ex,
u' = ex.
= ex.
0.25
36
TRUNG TÂM D Y THÊM
LÊ H NG PHONG
I2 =
=
= 1.
=e
3
1 + 1 = e.
:
3sinx + cos2x = 2 (1)
2
2sin x + 3sinx = 2
2sin2x 3sinx + 1 = 0
a
1
sinx = 1
0.25
0.5
0.25
=
* sinx = 1
0.25
sin
* sinx =
b
log
:
log
log
0.5
(2)
= log3x (x > 0).
(1)
0.25
: log3x
t
2.
2
x
0.25
9.
.
2
4
,
>0
a
0.5
,
(
)
!
:
!(
(
)
!
)! (
)!
.
!
!(
n 2 + 6 = 15
n = 11.
.
=
=
)!
0.25
.( ) .
2
.
.
k = 9.
2
trong khai tri
0.25
.
( ).
8
.
b
,
4
ng A
0.5
.
,
.
.
= 70
"
C
".
.
= 30.
37
:
0.25
38
TRUNG TÂM D Y THÊM
LÊ H NG PHONG
= (A; B)
(A2 + B2 > 0)
CD: A(x + 3) + B(y + 3) = 0
Ax + By + 3A + 3B = 0.
A
B
M
0.25
D
C
: SBCD = SACD = 18
d(A; CD) =
d(M; CD) =
0.25
25(36A2 + 48AB + 16B 2) = 90(A2 + B2)
810A2 + 1200AB + 310B 2 = 0
*
:
= 3
.
A=1
(CD): x
: CD2 = 90
(3d + 9)2 + (d + 3) 2 = 90
D(6; 0) (
) hay D( 12; 6) (
).
(
*
:
;
)
3y 6 = 0
D(3d + 6; d)
(d + 3)2 = 9
d = 0 hay d = 6
(6; 0)
A(0; 2)
0.25
B( 3; 1).
= 27
;
A = 31
(
CD: 31x
27y + 12 = 0
(
)
)
(
0.25
)
B( 3; 1).
()
8
:
: 2
(1)
(
x
2
)
0
0.25
.
: (2)
(3)
=
.
: (3)
Khi x =
*
1.0
( )
2t = t
(
)
(
)
0.25
2
(
y=
0
2
x=2
0
y = 0.
y=0
;
,
0.25
.
)
= 2.
;
39
= 2, y = 0
.
.
0.25
TRUNG TÂM D Y THÊM
9
LÊ H NG PHONG
2
Cho x,
P= (
*
(
* 4 = (12 + 12)(x2 + y2)
3
3
1.0
)
(
)
(x + y)2
3
2(x + y )
:
)
(
,
+ y2 = 2.
2
3
= x3 + y3.
x+y
.
(x + y)(x + y )
.
)
0.25
3
.
3
x +y
2.
.
;
:
= (x2 + y2)3 = x6 + y6 + 3x2y2(x2 + y2)
= x6 + y6 + 6x2y2 = (x3 + y3)2 2x3y3 + 6x2y2
2x3y3 6x2y2 = t2 8
* 2(x3 + y3) = (x3 + y3)(x2 + y2) = x5 + y5 + x2y3 + x3y2 = x5 + y5 + x2y2(x + y)
x5 + y5 + x2y2(x + y) = 2t.
*2
P
3
= (
=
=
=
0.25
)
4x3y3 + 12x2y2 + 5(x5 + y5) + 5x2y2
3 3
2 2
5
5
0.25
2 2
2(2x y 6x y )+ 5(x + y ) + 5x y
2(t2 8) + 5[x5 + y5 + x2y2(x + y)] =
f '(t) = 4t + 10; f '(t) = 0
t=
;
2t2 + 10t + 16 = f(t).
.
: f(2) = 28;
.
()
( )
0.25
()
;
;
40
.