... 122x2x1x2x22++>122x4x22+ > x2x2x2x22+> 0 x (x - 2) > 0 x > 2 hoỷc x < 0 (1) f(x) <432x2x1x2x22++<43 4x2 - 8x + 4 < 3x2 - 6x + 6 x2 - 2x - 2 < ... (x - 1)2 - 3 < 0 (x -1 + 3) (x - 1 -3) < 0 1 - 3 < x < 1 + 3 (2)Tổỡ (1) vaỡ (2) suy ra 21 < f(x) < 43 1 - 3 < x < 0 hoỷc 2 <x < 1 + 3 Baỡi ... Vồùi x1 = 1, x2 >1 thỗ f(x1) = 0, f(x2) > 0 nón f(x1) < f(x2) - Nóỳu x 1, ta coù ( )( )21x111xf+=Vồùi 1 < x1 < x2 thỗ 0 < x1 - 1 < x2 - 1 nón:...