/sci/ - Science & Math

we're supposed to show that
[math]X=\begin{pmatrix}1\\ 2\end{pmatrix}e^{-5t}[/math]
is a solution to
[math]\frac{dx}{dt}=3x-4y[/math]
[math]\frac{dy}{dt}=4x-7y[/math]

However, when I try to compute it as shown in the textbook, I wind up with
[math]AX=\begin{pmatrix}-e^{-5t}\\ -6e^{-5t}\end{pmatrix}[/math]
which is definitely not what it says I should get
[math]AX=\begin{pmatrix}-5e^{-5t}\\ -10e^{-5t}\end{pmatrix}=X'[/math]

what am I fucking up here