... 8x 3 1 6 2x 2x 1 8x+ + = + + <=> 2 23( 8x 3 8x 8x 4) 8x 1+ + = <=> 3(8x - 1) = (8x - 1)(2 28x 3 8x 8x 4+ + + )<=> (8x - 1)(2 28x 3 8x 8x 4+ + + - 3) = 0<=> ... 3,0x + y = 3 <=> y = 3 - x. Ta cã x 0y 1≥≥ => x [ ]0;2∈.0,5Thay vµo P: P = x3 + 2(3 - x)2 + 4x(3 - x) - 5x + 3x2 = x3 + x2 - 5x + 18.0,5XÐt f(x) = x3 + x2 ... điểmCâu 1:6,0a. (m - 3)x + ( 2- m)x + 3 - m = 0 (1).3,0ĐK: x 0; Đặt t = x , t 0.0,5(1) trở thành: (m - 3)t + (2 - m)t2 + 3 - m = 0 <=> m = 222t 3t 3t t 1 + + (2)0,5Xét...