lf `alpha and beta` are the roots of the equation `x^2-ax + b = 0 and A_n = alpha^n + beta^n`, then which of the following is true ?
A. `A_(n+1) = a A_(n) + b A_(n-1)`
B. `A_(n+1) = b A_(n) + a A_(n-1)`
C. `A_(n+1) = a A_(n) - b A_(n-1)`
D. `A_(n+1) = b A_(n) - a A_(n-1)`
