thuQc hai nhrlnh cira d6 thi khi PT (2) c6 hai nghiOm \,t2 thda mdn fi<0<tr.Do i16
/r\
2m.l-:l<0 em>0.J
\2)
sai n,, tr-rrrrl
-* I i1i rirp "ị t 'lirt lrit;,t.,; i - tl j t, I
.r'- I '
11) ,r,ir;; t'irt iliun iluttit kui nhtinh t'ilrt ({') .ttio
.lr l,!t,ttttr..i ..r',..ii , :, t t ltin,,.i lit tt,.:iitt ,,lltit
l-i) (ior {1fi lt tiurinll tlt,ttti: qttLt .ltI ; 0) , , iti s,)
t:ií k'íirt l, tk: {d} ,'i:r ({') tti ltni iliint .t, l"i.i,.,,.,. itrti ttltit;.'! t'l/lt { ( } ii/rr r llrt l",i - -] I \:. .i,.,,.,. itrti ttltit;.'! t'l/lt { ( } ii/rr r llrt l",i - -] I \:.
Ldi gidị a) Ggi P vir Q Dn luqt ld c6c di6m thuQc nh6nh ph6i vd nh6nh trbi cila (O thi
r(r*,, r * 1)t,, o); o[r +,;])tb, o),
pe, : fu + bl2 .{ !*])' = 4ab +{> 2+, = 4ab +{> 2+, \/(ab)ab la=b I minPQ=ZJO o1, 36 e s-b:J1. l+aD : - lab ua, 4, + ^,6;1 * ..6), fr - Jl ;, - "'5)
b) PT cua (Q: y = k(x-t). pr hodnh dQ giao diem cua (d) vd (O le * *? =i(x- l) x-l (-- - t ^ )o*' -ltr'-(2k+l)r+fr-2=O (l)
DAt t = x-1. Thay vdo PT (1) ta duqc ktz -t -3 = 0 (2) OC a cht (O tai hai nh6nh cira (Q thi PT (1) c6 hai nghiqm th6a m5nxl < I < x,
<+ PT Q) c6hai nghiOm th6a mdn
rr<0<,ro;<0<+k>0 (*)Ta c6 M(x,;yr), N(xz;!z) ndn7fr = (x, -1; y); Ta c6 M(x,;yr), N(xz;!z) ndn7fr = (x, -1; y); lfi = (*, -t; yr). Vfr = -2AN <> x1 - t: -2(x, -t) (3) 2k+l k-2 x1* x2: '- (4) xtxz: j (5) kk
Tt (3) ve (a) tim duoc xt, xz sau cl6 thay vdo (5) tim dusc fr =Z 6h6amdn didu kiQn(*)). D
J
[rA\-G 3. T{nh chrit rtia ildp uyin ttli tli1mrt'l $tt'"i trin {{-) rt'l $tt'"i trin {{-)
* Ihi tlg 4. ('1.,t ltiu;t.r,j .t = ,t i t,;i-- \-
Go,i I ii;4itxt dicnt t'tru itui li)nt t'dn, ivl.lu m6t r1idnr lrrin ttl) Ticp trn,en lai h'{ tuo đ lhi tC)
t'ii hui dirín,q tiiw t'dtt trri P vi {).
al {'hirng ii t'ittg l,{ !,r tt't;ri,ti,ltr)rtt ttnt PQ vit
tliin tiíh ttutr *itit' f l'Q liltittg &tịb) Drr tt'in tiri rhi ((^i t{iim ll suo clto b) Drr tt'in tiri rhi ((^i t{iim ll suo clto
',lP lQ lr l.
Ldi gidịra c6 (1 ; .2), t r(*02&:l € (c),
I l-xo /