DK:x≠0⇔(x+1)√2x2+2x+1+(x−1)√2x2−2x+1−5=0⇔(x+1)[√2x2+2x+1−(2x+12)]+(x−1)[√2x2−2x+1−(2x−12)=0⇔(34−2x2) (.......)=0⇒2x2=34⇔x=±√83hoặc đỏ=0 ( loại)
DK:x≠0⇔(x+1)√2x2+2x+1+(x−1)√2x2−2x+1−5=0⇔(x+1)[√2x2+2x+1−(2x+12)]+(x−1)[√2x2−2x+1−(2x−12)=0⇔(34−2x2) (.......)=0$\Rightarrow \frac{2}{x^2}=\frac{3}{4}\Leftrightarrow x=\pm \sqrt{\frac{8}{3}}
=\pm \frac{2\sqrt{6}}{3}$hoặc đỏ=0 ( loại)