... AB.AH + AD.AK = AC2.HƯỚNG DẪN CHẤM THI Nội dung đáp án ĐiểmBài 1a 2,03x2 – 7x + 2 = 3x2 – 6x – x + 2 = 1,0= 3x(x -2 ) – (x - 2) 0,5= (x - 2)(3x - 1). 0,5b 2,0a(x2 + 1) – x(a2 ... 12120,25Bài 3 5,0a 2,59x2 + y2 + 2z2 – 18x + 4z - 6y + 20 = 0⇔(9x2 – 18x + 9) + (y2 – 6y + 9) + 2(z2 + 2z + 1) = 0 1,0⇔9(x - 1)2 + (y - 3)2 + 2 (z + 1)2 = 0 (*) 0,5Do : 2 ... - 1). 0,5b 2,0a(x2 + 1) – x(a2 + 1) = ax2 + a – a2x – x = 1,0= ax(x - a) – (x - a) = 0,5= (x - a)(ax - 1). 0,5Bài 2: 5,01a 3,0ĐKXĐ : 222 32 04 0 02 0 233 02 0xx xx...