Which condition makes a 2×22 \times 22×2 matrix A=(abcd)A = \begin{pmatrix} a & b \\ c & d \end{pmatrix}A=(acbd) non-invertible?
ad−bc=0ad - bc = 0ad−bc=0
a=d,b=ca=d, b=ca=d,b=c
a+d=0a+d = 0a+d=0
ad−bc≠0ad - bc \neq 0ad−bc=0