Chapter 4.2, Problem 28P

In each of problem 28 through 38, use method of reduction of order to find a second solution $y$ of the given differential equation such that $\{y_1,y_2\}$ is a fundamental set of solution on the given interval.

$a{y}^{″}+b{y}^{\prime }+cy=0$, where $b^2-4ac=0$; $y_1=e^{-\frac{bt}{2a}}$