\(\eqalign{ & 2{x^2} + 8x + 6 = \sqrt {\frac{{x + 4}}{2}} \cr & \Leftrightarrow {x^2} + 4x + 3 = \sqrt {\frac{{x + 4}}{2}} \cr & \Leftrightarrow {x^4} + 8{x^3} + 22{x^2} + 24x + 9 = \frac{{x + 4}}{2} \cr & \Leftrightarrow 2{x^4} + 24{x^3} + 44{x^2} + 48x + 18 - x - 4 = 0 \cr & \Leftrightarrow 2{x^4} + 24{x^3} + 44{x^2} + 47x + 14 = 0 \cr} \)
(tự tiếp)