Ta có:
$\sqrt{5x^2-4x-6}=3\sqrt{x}+\sqrt{x^2-x-2}$
$\Leftrightarrow 5x^2-4x-6=x^2-x-2+9x-6\sqrt{x(x^2-x-2)}$
$\Leftrightarrow 5x^2-4x-6=x^2+8x-6-6\sqrt{x(x^2-x-2)}$
$\Leftrightarrow 4x^2-12x-4=-6\sqrt{x(x-2)(x+1)}$
$\Leftrightarrow 2x^2-6x-2=-3\sqrt{x(x-2)(x+1)}$
$\Leftrightarrow 2(x^2-2x)-2(x+1)=-3\sqrt{(x^2-2x)(x+1)}$
$\Leftrightarrow (2\sqrt{x^2-2x}-\sqrt{x+1})(\sqrt{x^2-2x}+2\sqrt{x+1})=0$
có chỗ bị nhầm dấu
- phuongnamz10A2 yêu thích