Question

If the following system of equations was written as a matrix equation in the form AX = C, and matrix A was expressed in the form [a c
b d] , find the value of a - b + c + d.

Answer 1

2x+8y=7
4x-2y=9

Answer 2

matrix A is expressed in the form \[\left[\begin{matrix}a & b \\ c & d\end{matrix}\right]\]
is that correct?

Answer 3

I need to know if it's like i said or if it's in the form of [a c b d]

Answer 4

Yes

Answer 5

Its the first one
a c
b d

Answer 6

AX = C
\[\left[\begin{matrix}2 & 8 \\ 4 & 2\end{matrix}\right]\left(\begin{matrix}x \\ y\end{matrix}\right)=\left(\begin{matrix}7 \\ 9\end{matrix}\right)\]

Answer 7

can u see that a=2, c=8, b=4 and d=2?
now u can calculate a-b+c+d, try it yourself.

Answer 8

its not -2 on the bottom right ?

Answer 9

oh yeh it is, sorry i'm blind.

Answer 10

No its alright

Answer 11

So it would be 4 right

Answer 12

yep.

Answer 13

Thankss

Answer 14

no problem brook! I think the key to solving these type of questions is knowing how to put the equations into a matrix, u do know how to do it now right?

Answer 15

Nopp but I just found out, thank youu

Answer 16

ok, that's good. no problem.