Jessica D.

Solve each system of equations.
$4 a-2 b+8 c=30$
$a+2 b-7 c=-12$
$2 a-b+4 c=15$

$D=\left|\begin{array}{ll}{a} & {b} \\ {c} & {d}\end{array}\right|=$ _________.

A determinant can never equal 0.

If any row (or any column) of a determinant is multiplied by a nonzero number k, the value of the determinant remains unchanged.

find the value of each determinant.
$$
\left|\begin{array}{rr}{6} & {4} \\ {-1} & {3}\end{array}\right|
$$

find the value of each determinant.
$$
\left|\begin{array}{rr}{-3} & {-1} \\ {4} & {2}\end{array}\right|
$$