... l H 0.5 HL (d ) thi HL // OE, nờn + Ke OE AB , thi E l trung im cua AB (c inh) Ke HL l ng trung binh cua tam giac OEM, suy ra: HL = OE (khụng ụi) + Do o, M i ụng trờn (d) thi H luụn cach du ... 3, hoc Nờu a = thi d = v c = hoc c = , o abcd = 1b16 hay 1b36 v ( ) 1bc6 = x ( ) 2 hay x Ta co: 262 = 676; 342 = 1156; 362 = 1296; 442 = 1936; 462 = 2126 Chi chon c 1936 Nờu a = thi d = v c = ... 4489; 732 = 5329 Khụng chon c s no Võy chi co cac ch s a = 1, b = 9, c = 3, d = thoa iu kin bi toan 1.5 Bi 6x + + 3 x3 3x A= 3x ữ ữ a/ (2) 3 x x + x + ữ + x ữ Ta co: 3x + 3x + = (...