Answer:
18
Step-by-step explanation:
(must round down for population)


Multiply both numerator and denominator of
by the complex conjugate of the denominator, -2+9i.

Multiplication can be transformed into difference of squares using the rule:
.

By definition, i² is -1. Calculate the denominator.

Multiply complex numbers 5-3i and -2+9i in the same way as you multiply binomials.

Do the multiplications in
.

Combine the real and imaginary parts in -10+45i+6i+27.

Do the additions in
.

Divide 17+51i by 85 to get
.

The real part of
is
.

By letting

we get derivatives


a) Substitute these into the differential equation. After a lot of simplification, the equation reduces to

Examine the lowest degree term
, which gives rise to the indicial equation,

with roots at r = 0 and r = 4/5.
b) The recurrence for the coefficients
is

so that with r = 4/5, the coefficients are governed by

c) Starting with
, we find


so that the first three terms of the solution are
