Question

If a1=5 and an=an-1-4
a) -11
b) -7
c) 1
d) 5

Answer 1

The sequence is defined by an = an-1 - 4an-2. To find a12, substitute the values of a1 and a2 into the formula and simplify.

Step-by-step explanation:

The given sequence is:

5, 10, 15, 20, -1, -8, -7, -2, -9, -15, -18, -20, -7, -15, -22, -26, -29, -12, -21, -29, -34, -36, -23, -34, -44, -50, -52, -44, -59, -73, -82, -84

From the given sequence, we can see that each term an is equal to an-1 - 4an-2. So, to find a12, we can substitute the values of a1 and a2 into the formula.

a12 = a11 - 4a10 = -84 - 4(-82) = -84 + 328 = 244

Therefore, a12 is equal to 244.