This is a geometric sequence, so use the formula for the sum of a geometric sequence:
Sum = (a(r^n - 1))/(r - 1)
where a is the first term, -5
r is the common ratio, 5
and n is the number of terms
Thus,
Sum = ((-5)(5^6 - 1))/(5-1) = -19530
If u were to add 5x+20=9x you’d get x=5
You sleep 1/3 of the day.
The solution depends on the value of

. To make things simple, assume

. The homogeneous part of the equation is

and has characteristic equation

which admits the characteristic solution

.
For the solution to the nonhomogeneous equation, a reasonable guess for the particular solution might be

. Then

So you have


This means


and so the general solution would be
8*(n+6)=80
distribute
8n+48 = 80
subtract 48 from each side
8n = 32
divide by 8
n=4