If

then

The ODE in terms of these series is



We can solve the recurrence exactly by substitution:


So the ODE has solution

which you may recognize as the power series of the exponential function. Then

Answer:
first term = 2 ...(given)
second term = f (2) = f (2-1) * 5 = 1 * 5 = 5. .....[according to the formula f(n) = f (n -1) *5 ]
third term = f (3) = f ( 3 - 1 ) * 5 = 2 * 5 = 10
fourth term = f (4) = f (4 - 1) * 5 = 3 * 5.= 15
fivth term = f (5) = f ( 5 - 1) * 5 = 4* 5. =20
Arrange from smallest to largest
-25, -12/4, 1/5, 18/5, 10
chose the middle number
1/5