If an=2na_n = 2^nan=2n is a solution to an=c1an−1+c2an−2a_n = c_1 a_{n-1} + c_2 a_{n-2}an=c1an−1+c2an−2, which equation is valid?
2n=c12n−1+c22n−22^n = c_1 2^{n-1} + c_2 2^{n-2}2n=c12n−1+c22n−2
2n=c12n+c22n2^n = c_1 2^n + c_2 2^n2n=c12n+c22n
2n=c12n+1+c22n+22^n = c_1 2^{n+1} + c_2 2^{n+2}2n=c12n+1+c22n+2
2n=c12+c242^n = c_1 2 + c_2 42n=c12+c24