Answer:

Step-by-step explanation:
It is a linear homogeneous differential equation with constant coefficients:
y" + 4y = 0
Its characteristic equation:
r^2+4=0
r1=2i
r2=-2i
We use these roots in order to find the general solution:

Im taking stats right now i might be able to help.
Remember that you can do anything ot an equaiton as long as you do it to both sides
-8+x=0
add 8 to both sides
8-8+x=0+8
0+x=8
x=8
answer is B. 8
X-the $5 bills
y-the $10 bills
x+y=20
5x+10y=120
It's a system.
2 - 5x = -13
-2 -2
---------------
-5x = -15
/-5 /-5
-------------
x = 3
Hope this helps!