\ Prr oNG-c D &Dr-l{INu YtN oE BE CHINH THUC xrru rRA HQC rci' u NAU Hqc nt0N: roAN g 2017 - 2a18 Thdi gian ldnt bhi 90 phtit, khhng kA thdi gian giao di' I. TRAC NGHIpM (2,0 tli6m) drtng. Ghi vdo bdi tdm chi mQt cttib ctii A, B, C hofic D tlwdc yhuong tin trd ldi cAu 1. Phuong trinh nio sau t16y li phucrng trinh bac ntr6t rrai ry *,y? D.2x+5y=10 C.2+5=10 A.2x+5y2=1g B.Zxy+Sy=lg A Ciu Z.Cho parabo-l (f) ,y =+vi dudng thang(d) :! =Zx-3cit nhau tai hai di6m Khi d6, diQn tfch tam giitc OAB b{ng: c. s (dvd| ' cAu 3. Cho rtudmg trdn (o;n) c6 AB =JZn DO dai cung nh6 AB bing: A.6 (dvdt) 8.7 (dvdt) c6u 4. Cho mQt hinh cAu c6 thc tich bang 5002gnlza 8.50r [" 3 D. tA}r cm2 C.25tt cltt2 5 (1,5 tri6m). cho hQ phuong trinh: (mx-v=l - ..1 (*,v ln 6n; lrr li IT^;;, : z a) Gi6i hQ Phuong trinh vdi m = -3; b) Tim m d0 hQ cl nghiQm duy nhat Ciu ,rr'. Di€n tich mflt ciu d6 1i: 3 cm2 - Tu LU4.N'(8,0 cli6m) u. PrrAN ciu 50:o (dvdt) nR D.4 c"ry B.ZrR A. nR D.9 vi B' tham sd) y deu nh4n gi6 tri UY*n trinh: x' -Zna+4m-4= 0 (1), (x li dn; mli tham sO) (r;y) sao cho x vit 6 (1,5 tliam)Cho phuong a) Tim m d6 phuong trinh (1) c6 hai nghiQm ph6n biQt; b) Tim m d6 hai nghiQm x,;x, cria phucrng trinh (1) th6a rndn: ( n-2)(*'-2)=x" +x" -8' km, sau CAu 7 (1,5 rli6m). MOt ca nd xudi ddng tr6n mOt t0 -z e trro._.J*= r;*1>tt <>< " 2nt-2 lyroIlY=:--:-:>Q \r' t- a) A = l2nt-2>0 ln'+Z l*rl 0r5 m>1. (nt-2)2 Phucrng trinh ( 1) c6 hai nghiQrr phAn biQr x, ;x, khi: A' > 0 e(m-2)' r0e 0r75 m*2. b) Vdi moi m thi phucrng trinh (1) lu6n c6 hai nghiern- vi Theo h6 thric 6 (1,5 eli6m). - dt, ta c6: {x, |.', (x, -2)(x, -Z)=x,'+xr' o (r, **r)' (2m)' Ta co: ^I -8e + x, = 2nt '', =4nt-4 xtxz-2(n*xr)+4=(x, + *r)'-2xrxr-g 0,25 -3x,xr+2(xr+xr)=12 - 3.(4nt - 4) + 2.2m = t2 e 4m(nt - 2) = 0 fm=O lnt-) L"' vay m :0 hodc m:2. 0r5