The third one, not sure about any other ones.
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:

15x4y2 letter B is your answer
Answer:
28
Step-by-step explanation:
I will solve you system by substitution
y = 2x - 3 ; x + y = 1
→Step 1: Solve y = 2x - 3 for y
→Step 2: Substitute 2x - 3 for y in x + y = 1:
x + y = 1
x + 2x- 3 = 1
3x - 3 = 1 (Simplify both sides of the equation)
3x - 3 + 3 = 1 + 3 (Add 3 both sides)
3x = 4
3x ÷ 3 = 4 ÷ 3 (Divide each side by 3)
x = 4/3
→Step 3: Substitute 4/3 for x in y = 2x - 3:
y = 2x - 3
y = 2 (4/3) -3
y = -1/3 (Simplify both sides of the equation)
Answer:
x = 4/3 and y = -1/3
∫Hope that helps∫