If A and B are two non-singular matrices of same order, then which of the following statements are not correct ?

A. AB is non singular.

B. $(A+B)^{-1} = B^{-1}+A^{-1}$.

C. adj (AB) = adj B. adj A.

D. AB is not invertible.

Choose the correct answer from the options given below:

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If $A = \begin{bmatrix}\alpha & \beta\\r & \Delta\end{bmatrix}$, such that $|A| = 25$, then the value of $\left|\frac{1}{5}A\right|$ is.

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