? = 4/3 π(1 1/4)
<span>Answer: 8</span>
ANSWER
24
EXPLANATION
For a matrix A of order n×n, the cofactor
of element
is defined to be

is the minor of element
equal to the determinant of the matrix we get by taking matrix A and deleting row i and column j.
Here, we have

M₁₁ is the determinant of the matrix that is matrix A with row 1 and column 1 removed. The bold entries are the row and the column we delete.

Since the determinant of a 2×2 matrix is

it follows that

so 
Use substitution and substitute y into the other equation. One of the equations already gives you y in terms of x, so use that and substitute it into the other equation. y = 3x - 4
Plug into the other equation: -3y = -9x + 12
-3(3x-4) = -9x + 12
-9x + 12 = -9x + 12
This is an identity. So that means that any value of x makes this equation true. So B.
It can be written as 1.0625