Answer:
c=80
Step-by-step explanation:
Based on my reading the critical damping occurs when the discriminant of the quadratic characteristic equation is 0.
So let's see that characteristic equation:
20r^2+cr+80=0
The discriminant can be found by calculating b^2-4aC of ar^2+br+C=0.
a=20
b=c
C=80
c^2-4(20)(80)
We want this to be 0.
c^2-4(20)(80)=0
Simplify:
c^2-6400=0
Add 6400 on both sides:
c^2=6400
Take square root of both sides:
c=80 or c=-80
Based on further reading damping equations in form
ay′′+by′+Cy=0
should have positive coefficients with b also having the possibility of being zero.
Answer:

Step-by-step explanation:


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Answer:
Katie is 6 years old and Thomas is 3 years old
Step-by-step explanation:
Given that we should let K and T be the current ages of two siblings, Katie and Thomas.
If Katie is currently twice the age of Thomas then,
K = 2T
and in 6 years, Katie will be 4 times Thomas's current age then
K + 6 = 4T
Solving both equations simultaneously by substituting the value of K given in the first equation into the second
2T + 6 = 4T
Collect like terms
6 = 4T - 2T
6 = 2T
Divide both sides by 2
T = 3
Recall that K = 2T
K = 2 * 3
= 6
Hence Katie is 6 years old while Thomas is 3 years old
Answer:
Thank you
Step-by-step explanation: