Find the value of the determinant of the matrix [[1,2],[3,4]].
Correct: A
The determinant of the 2x2 matrix [[a,b],[c,d]] is given by the formula ad - bc. For the given matrix, a = 1, b = 2, c = 3, and d = 4, so the determinant is (1)(4) - (2)(3) = 4 - 6 = -2.