x4+2x2+1=5x2 হলে x+1/x=কত?

x⁴+2x²+1=5x² হলে x+1/x=কত?

A √3

B 2

C 5

D √5

Correct Answer: Option D

x⁴+2x²+1=5x²
or,x⁴+1=3x²
or,x²(x²+1/x²)=3x²
or,x²+1/x2=3
or,(x+1/x)² - 2.x.1/x=3
or,(x+1/x)²=3+2=5
∴ x+1/x=√5