Question

Use the matrix tool to solve the system of equations. Choose the correct ordered pair.

4x + y = 0
8x - y = 6
A. (2, -8)
B. (1, -4)
C. (,1/2 -4)
D. (,1/2 -2)

Answer 1

d

Answer 2

any other answers I wanna make sure this is corrcet

Answer 3

The inverse of a 2 by 2 matrix [a b; c d] is [d -b; -c a]. So switching the elements on the main diagonal and inverting the signs of the other two gives the inverse as [-1 -1; -8 4].

The determinant of a 2 by 2 matrix is ad-bc = (4)(-1) - (8)(1) = -12.

So the inverse is 1/-12 [-1, -1; -8, 4].

Multiplying this by the solution matrix [0,6] gives 1/-12 [6,24] so x = 1/2 and y = -2.