Final answer:
The determinant of the matrix [[7,2],[-4,-9]] is calculated using the formula ad - bc, resulting in a determinant of -55.
Step-by-step explanation:
To evaluate the determinant of the matrix [[7,2],[-4,-9]], we use the formula for the determinant of a 2x2 matrix: ad - bc, where a, b, c, and d are the elements of the matrix such that it can be represented as [[a, b], [c, d]].
The determinant of the given matrix is calculated as:
Applying the formula:
Determinant = ad - bc
Determinant = (7 * -9) - (2 * -4)
Determinant = -63 - (-8)
Determinant = -63 + 8
Determinant = -55
The determinant of the matrix is -55.