Theorem T36 Let FnF_nFn be the Fibonacci numbers. Then Fn+12=4FnFn−1+Fn−22 ,n≥2.F_{n+1}^2 = 4 F_n F_{n-1} + F_{n-2}^2 \; , \quad n \geq 2. Fn+12=4FnFn−1+Fn−22,n≥2.