Answer:
91.5
Step-by-step explanation:
I did the math. Add up all the numbers and then, divide the result by two to get 91.5
Distance = speed x time
speed = distance/time
time = distance / speed
400m/36s = 11 1/9 m per second
Answer: 60 different numbers can be formed
Step-by-step explanation:
Note that we have 5 different digits, and we must select 3 of them. They should not be repeated
The order of selection is important in this case, because the number 532 is not the same as the number 235.
So we have a permutations problem, where we have a set of n elements and we want to choose r from them.
Then we define the permutacion as:

In this case note that n=5 because there are 5 elements in the set.
r = 3 because we combine the elements to form three-digit numbers
Then:





Answer:
a) x=(t^2)/2+cos(t), b) x=2+3e^(-2t), c) x=(1/2)sin(2t)
Step-by-step explanation:
Let's solve by separating variables:

a) x’=t–sin(t), x(0)=1

Apply integral both sides:

where k is a constant due to integration. With x(0)=1, substitute:

Finally:

b) x’+2x=4; x(0)=5

Completing the integral:

Solving the operator:

Using algebra, it becomes explicit:

With x(0)=5, substitute:

Finally:

c) x’’+4x=0; x(0)=0; x’(0)=1
Let
be the solution for the equation, then:

Substituting these equations in <em>c)</em>

This becomes the solution <em>m=α±βi</em> where <em>α=0</em> and <em>β=2</em>
![x=e^{\alpha t}[Asin\beta t+Bcos\beta t]\\\\x=e^{0}[Asin((2)t)+Bcos((2)t)]\\\\x=Asin((2)t)+Bcos((2)t)](https://tex.z-dn.net/?f=x%3De%5E%7B%5Calpha%20t%7D%5BAsin%5Cbeta%20t%2BBcos%5Cbeta%20t%5D%5C%5C%5C%5Cx%3De%5E%7B0%7D%5BAsin%28%282%29t%29%2BBcos%28%282%29t%29%5D%5C%5C%5C%5Cx%3DAsin%28%282%29t%29%2BBcos%28%282%29t%29)
Where <em>A</em> and <em>B</em> are constants. With x(0)=0; x’(0)=1:

Finally:
