Answer:
A=-2 and f(A)=10
Step-by-step explanation:
[tex]det\left[\begin{array}{cc}a&b\\c&d\end{array}\right] =ac-bd[/tex]
therefore
[tex]det\left[\begin{array}{cc}1&2\\3&4\end{array}\right] =(1)(4)-(2)(3)=4-6=-2[/tex]
now evaluate [tex]f(-2)[/tex]
[tex]f(x)=2x^2-6x-10[/tex]
[tex]f(-2)=2(-2)^2-6(-2)-10[/tex]
[tex]f(-2)=2(4)+12-10[/tex]
[tex]f(-2)=8+2[/tex]
[tex]f(-2)=10[/tex]
