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1. $y=\frac{-2x+1}{x-2} $. Viet phuong trinh d qua tam doi xung cua C voi he so goc k. Voi gia nao cua k thi d khong cat C.
2. chứng minh : $2 < \frac{2x^2+2x+3}{x^2+x+1} < \frac{10}{3} $
3. Trong mp Oxy cho elip co tam sai $\frac{3}{5} $ va cac ban kinh qua tieu diem M nam tren E la 4 va 6 . Viet pt chinh tac cua E . Goi A,B la 2 diem thuoc E sao cho $AF_1 + BF_2=12$. Tính $AF_2+BF_1$ ( $F_1 , F_2$ la tieu diem cua E)
4. Trong khong gian $Oxyz$ cho 3 diem $S(1,0,-2); A(-1,2,-2); B(0,1,-4)$. Xd toa do $C,D$ sao cho $ABCD$ la hinh binh hanh nhan $I(-3,1,0)$ lam tam. Tu do tinh the tich $S.ABCD$.
5. a/ Cho hai so phuc $z_1, z_2$ thoa $(z+2-i)^2 -6(z+2-i)+13=0$ tính $A=z_1^2+z_2^2$
b/ Tim cac so thuc x,y thoa $x(3+5i)+y(1-2i)=7-2i$
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