Solve the initial value problem 8(t+1) dy/dt


−6y=12t for t>−1 with y(0)=17. Find the integrating factor, u(t)=

EVESUNER8570

1 answer

To solve this initial value problem, we first need to put the equation in the standard form of a linear first-order ordinary differential equation: dy/dt + P(t)y = Q(t). The given equation can be rearranged to this form by dividing both sides by 8(t+1):

dy/dt - (6/8(t+1))y = (12t)/(8(t+1))

Comparing this to the standard form, we have P(t) = -(6/8(t+1)) and Q(t) = (12t)/(8(t+1)).

To find the integrating factor, we use the formula u(t) = e^(∫P(t)dt). In this case, P(t) = -(6/8(t+1)), so we have:

∫P(t)dt = ∫-(6/8(t+1))dt
= -(6/8)∫(1/(t+1))dt
= -(6/8)ln|t+1| + C,

where C is the constant of integration.

Therefore, the integrating factor is u(t) = e^(-(6/8)ln|t+1| + C)
= e^(-(3/4)ln|t+1| + C)
= e^(ln|t+1|^(-3/4) + C)
= e^(ln|t+1|^(-3/4)) * e^(C)
= |t+1|^(-3/4) * e^(C).

Since ln|t+1| and C are constant terms, e^(ln|t+1|^(-3/4)) * e^(C) is also a constant.

Therefore, the integrating factor for this initial value problem is u(t) = |t+1|^(-3/4) * constant.