I've come this far:
an = 4an-1 + 5an-2
a1 = 2
a2 = 6
roots
x1 = 5
x2 = -1
I insert roots in : an = U*s1^n + V*s2^n
which gives : an = 4*5^n + 5*(-1)^n
what now?
an could e.g. be a1?
Hello MadspeterThanks for showing us your working so far. What you mean is:
$\displaystyle a_n = U{x_1^n} + V{x_2^n} = U.5^n +V.(-1)^n$
Then plug in the values $\displaystyle n = 1, n = 2$:
$\displaystyle a_1 = 2= 5U -V$
$\displaystyle a_2 = 6 = 25U + V$
Can you complete it now?
Grandad