内容正文:
拓展与延伸18
与斜率有关的常用结论
(-〕
c
垫
R
型
区
I
|之
区
一区
12
米
食
图
】
】
A(-2,0),A(2,0)
2
P(x,x≠±2)
=1
4
3
2
PAPA=-4
3
,-2
2-4
食
3-8
≤kA
≤
3-
0
菜
bo
垂
bom
22
9
(1,
-1,2
(1,3)
-1,-4)
x+x2 y+y2
A(xy),B(x2:y2)
AB
2’2
为+2
飞B=片业,k=
=+2
2
9
2
X1-X2
X1+X2X1+X2
2
y2=1
2
A,B
--。-0
阳k=片兰-9
2
9
k=1,k4B=9
y=9x-8
AB:y=9x-8
x=
72x2-2×72x+73=0
△=(-2×72)2-4×72×73=-288<0
95
y=-
9
9
5
22
k=-2,ka=
AB:y=-
2
2
r_y=l
9
45x2+2×45x+61=0
△=(2×45)2-4×45×61=-4×45x16<0
k=3,kB=3
AB:y=3x
a=1,b=3
AB:y=3x
-9
7
4
k=4,kB
9-4
9
AB:y=x-
4
4
x2
=1
63x2+126x-193=0
△=1262+4×63×193>0
22
=1
P(2,1)
2
R:B
P
PP
y=4x-7
2x2-y2=2
P(x,y),P(x2,y2),
2x22-y2=2
2x2-y2=2
2x2-y2=2
(x1,)(x2,2)
2x2-y22=2
2(x+x3x-x2)-(y+y2)0-2)=0
X1+七2=4,+y2=2
8(x-x2)-2(0y-y2)=0
X1≠X2
y-2=k=4
X1-X2
y-1=4(x-2),y=4x-7
现
AB
PB
k
母
母
AB
金
维
险
AB
7
1
C·
B
P(0,1)
昂
1
t≠0
<2
4到
+-4F-24-F2.-
2t
2t
t=2
y=+mm≠1
y=a+m
4+少=1
(4k2+1)x2+8kx+4m2-4=0
△=16(42-m2+1>0
8km
4m2-4
4k2+1
4k2+1
k+k=上-1+-1_@+m-1+c,+m-l_25+m-x+
x
X2
X
X2
XX2
k+k2=-1(2k+1xx2+(m-10(x+x2)=0
2法切a-我-0
m+1
m>-1
△>0
2
m+1
2
x+m
1-2
y2=4x
kADk=2.
A1,2)D(x,,E(x,2
x=my+n(m≠0
y2-4my-4n=0
△=16(m2+m)>0,片+y2=4m,5=-4n
kD·kE
4-2-2=2
x-1x2-1
=4x,=4x%+2(以+2)=4
n=2m-1
x=my+2m-1(y+2)m=x+l
(-1,-2.
〔)
利
鱼
型
盘
⑧
8
5
户
壬
罗
杂
业
进
贸
逊
鑫
√
mx2+y2=1
y=1-x
MN
2
s
52
2W3
92
2W5
3
2
27
M(,y),N(x2,y2)
mx2 +ny =1,mx +ny =1
m(x2-x)+n(-y)=0
mx2+ny2 =1
y=1-x
m
y+业.乃-业=-m
X1≠X2
x-x号
n
X1+X2x1-X2
n
MN
(Xo,Yo)
x+x32=2x,片+y2=2y0
y-2=k=-1
x1-X2
MN
2
=2
2
2
n 2
A(2,1)
C.
2y=1a>0
a a-1
1 C P O
AP
,AQ
41
A
a2a2-
=1
a-4a2+4=0
a2=2
y2=1
l:y=kx+m
2
P(x
4km
y),O(x2 y2)
(2k2-1)x2+4Kx+2m2+2=0
x+X2=-
2k2-1
X3
2m2+2
2k2-1
k+k0=号+少}+m1+@+m-1-0
x-2x2-2x1-2
七2-2
2xx2+(m-1-2k)x+x2)-4(m-1)=0
4m1-
4m-1)=0
(k+1)(m+2k-1)=0
A
k=-1
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