Find value of X for which matrices A does not have an inverse

Question

A = x 5

1 3

how is this meant to be solved or explained why it can't?

Answer 1

If the determinant is zero, the matrix has no inverse, so set the determinant equal to zero and solve for x.

A = | x 5 |

| 1 3 |

det(A) = x(3) - 1(5) = 0

3x - 5 = 0

x = 5/3