A2. a.
Aˣₓ₊₄ = (x+4)! /x!·4!
Aˣ⁺²ₓ₊₃ = (x+3)! /(x+2)!
Ecuatia de la punctul a. devine
(x+4)! /x!·4! = 1/2 ·(x+3)! /(x+2)! <=>
(x+1)·(x+2)·(x+3)·(x+4) = 1/2 ·(x+3) <=>
(x+1)·(x+2)·(x+4) = 1/2 (deoarece se reduce x+3 care este diferit de 0 ).
(x²+3x+2)·(x+4) = 1/2
x³+7x²+2x+8 = 1/2
x³+7x²+2x +15/2 = 0 si afli solutia.
Analog celelalte subpucte.
