Answer:

Step-by-step explanation:

Answer:
9/20 yes, 4/15 not. See below
Step-by-step explanation:
Pick 9/20 and multiply numerator and denominator by 5:
9/20 = 45/100
We know that if we divide a number by 100 we need to move the coma as two places left, so:
9/20 = 45/100 = 0.45
And this is a terminal decimal as we know where it ends.
On the other hand if we pick 4/15 let try to divide it (here I will do it 'manually'):
4 |_ 15
we can divide 4 by 15, so we use 40 and begin with a comma
40 |_ 15
0.
15 enters 2 times in 40 with a rest of 10, so:
40 |_ 15
30 0.2
100
100 divided by 15 is 6 and we have 10 as rest again, and again and again...
40 |_ 15
30 0.266.....
100
100
....
So, we will have 0.266666666666666 infinitely. The decimal for 4/15 is non terminating and is 0.26666666666666666...
The characteristic solution follows from solving the characteristic equation,

so that

A guess for the particular solution may be

, but this is already contained within the characteristic solution. We require a set of linearly independent solutions, so we can look to

which has second derivative

Substituting into the ODE, you have



Therefore the particular solution is

Note that you could have made a more precise guess of

but, of course, any solution of the form

is already accounted for within

.
I believe the commission is 7,511