... ng thng cú phng trỡnh (P): 3x + 12 y - 3z - = v (Q): 3x - y + z + = (d1): x + y - z +1 = = , -4 (d2): x - y +1 z - = = -2 Vit phng trỡnh ng thng (D) song song vi hai mt phng (P), (Q) v ct (d1), ... C v D 2) Trong khụng gian vi h ta Oxyz, cho D ABC vi ta nh C(3; 2; 3) v phng trỡnh ng cao AH, phng trỡnh ng phõn giỏc BD ln lt l: x-2 y -3 z -3 x -1 y - z - = = , d2 : = = 1 -2 -2 Lp phng ... -1 + 2Cn -2 = Cn +3 - Cn -3 - Cn -2 26 MATHVN.COM - www.mathvn.com s 27 I PHN CHUNG CHO TT C TH SINH (7,0 im) Cõu I (2 im) Cho hm s: y = x - (2m + 1) x + 2m (m l tham s ) 1) Kho sỏt s bin thi n...