Question

HELPPP!! matrices!!! i will write the problem down...

Answer 1

\[\left[\begin{matrix}4 & -a \\ 7 & 3a\end{matrix}\right]=57\]

Answer 2

Matrices can be done in a calc.

Answer 3

i assume you mean the determinant is 57 and you want to solve for
"a" yes?

Answer 4

are you looking for the determinant or something?

Answer 5

but i want to learn it manually...it says solve for the variable...

Answer 6

\[4(3a)-(-a)(7)=57\]

Answer 7

must be right? ok take the determinant . it is
\[4\times 3a-7\times(-a)=12a+7a=19a\]

Answer 8

myininaya does not like my times signs i know.

Answer 9

lol...so wait you just cross multiply??