jika determinan matriks A adalah 7 dan A=(x x+1) (x-1 x+3),maka x = . . . kurung diatas dan kurung di bawah nyambung.

[tex] \left[\begin{array}{ccc}x&x+1\\x-1&x+3\end{array}\right] =7 dideterminankan: x.(x+3)-(x-1)(x+1)=7 x^2+3x-x^2+1=7 3x+1=7 3x=6 \boxed {x=2}[/tex]

Pembuktian!
[tex] \left[\begin{array}{ccc}2&2+1\\2-1&2+3\end{array}\right] =7 2.5-1.3=7 10-3=7 7=7 \boxed {terbukti}[/tex]