Answer
Given a square matrix, $A$, if a multiple of one row of $A$ is added to another row to produce a matrix $B$, then det $B$ = det $A$.
Work Step by Step
Given a square matrix, $A$, if a multiple of one row of $A$ is added to another row to produce a matrix $B$, then det $B$ = det $A$. In this case, $-2$ times Row 1 was added to Row 2 in matrix $A$ to get matrix $B$. Thus, det$A$ = det $B$.