Plugging the equation $y''+y'=0$ into Wolfram Alpha yields the following solution:
$$y(x) = c_2-c_1 e^{-x}.$$
This has me stumped because my textbook states that in the case of $b^2-4ac > 0$.
"If root 1 $r_1$ and root 2 $r_2$ are two real and unequal roots to the auxiliary equation $ar^2 + br + c =0$, then
$$y = c_1e^{r_1x} + c_2e^{r_2x}$$
is the general solution."
Based of my book, the solution to the above problem would be
$$y=c_2+c_1 e^{-x}$$
so which one's right?