... Ta cú: 5 Gi s phng trỡnh chớnh tc ca elip cú dng: 2 ổ ổ ã F1 MF2 = 900 MF12 + MF22 = F1 F22 ỗ + x ữ + ỗ - x ữ = 64 ứ ố ứ ố 0, 25 0, 25 0, 25 0, 25 0, 25 0, 25 0, 25 0, 25 0, 25 0, 25 0, 25 0, 25 0, 25 www.VNMATH.com ... b;2 - 3b; -3b ) , C ( -1 + 5c;1 + 2c; -1 + c ) Theo gi thit AB = BC nờn B trung im AC ú: 8b 0, 25 0, 25 0, 25 0, 25 0, 25 ỡ2 x B = x A + x C ỡ2b = -1 + a + 5c ỡ a - b + 5c = ỡa = ù ù ù ù ớ2 yB = y ... x = 0, 25 (b) iu kin: x kp , x 0, 25 iu kin: x = y = -1 - x - < (*) 0, 25 0, 25 0, 25 0, 25 0, 25 0, 25 WWW.VNMATH.COM ( ) Th vo (2) ta cú: ( ) x + y = xy x + + x - x + y = xy ( x - y ) 0, 25 x ổxử...