91Ó°ÊÓ

Apply the Cramer’s rule for the value of x.

$x=\frac{\left|\begin{array}{cc}e& b\\ f& d\end{array}\right|}{\left|\begin{array}{cc}a& b\\ c& d\end{array}\right|}$

Substitute 1 in place of a, 2 in place of c, $-4$ in place of b, 3 in place of d, 1 in place of e and 13 in place of f into role="math" localid="1647359635895" $x=\frac{\left|\begin{array}{cc}e& b\\ f& d\end{array}\right|}{\left|\begin{array}{cc}a& b\\ c& d\end{array}\right|}$and perform simplification of determinants to write the value of x.

$\begin{array}{c}x=\frac{\left|\begin{array}{cc}1& −4\\ 13& 3\end{array}\right|}{\left|\begin{array}{cc}1& −4\\ 2& 3\end{array}\right|}\\ =\frac{1â‹\dots 3−\left(−4\right)â‹\dots 13}{1â‹\dots 3−\left(−4\right)â‹\dots 2}\\ =\frac{55}{11}\\ =5\end{array}$

Apply the Cramer’s rule for the value of y.

$y=\frac{\left|\begin{array}{cc}a& e\\ c& f\end{array}\right|}{\left|\begin{array}{cc}a& b\\ c& d\end{array}\right|}$

Substitute 1 in place of a, 2 in place of c, $-4$ in place of b, 3 in place of d, 1 in place of e and 13 in place of f into role="math" localid="1647359841972" $y=\frac{\left|\begin{array}{cc}a& e\\ c& f\end{array}\right|}{\left|\begin{array}{cc}a& b\\ c& d\end{array}\right|}$and perform simplification of determinants to write the value of y.

$\begin{array}{c}y=\frac{\left|\begin{array}{cc}1& 1\\ 2& 13\end{array}\right|}{\left|\begin{array}{cc}1& −4\\ 2& 3\end{array}\right|}\\ =\frac{1â‹\dots 13−1â‹\dots 2}{1â‹\dots 3−\left(−4\right)â‹\dots 2}\\ =\frac{11}{11}\\ =1\end{array}$

The obtained value of x is 5 and y is 1 so the solution is $\left(5,1\right)$.