How can we prove the following matrices inequality?

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Let $A$ and $B$ be two matrices $(nxn)$. How can we prove the following inequality? I have really no idea about how to prove it. Can you give me some hints?

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It seems to be false. A counter-example is: $n=4$, $B=2I_4$, $A=I_4$, and $\|M\|=\max_{\|x\|_2=1} \frac{\|Mx\|_2}{\|x\|_2}$. Then $(A+B)^n-A^n=(3^n-1) I_4$. So, $\|(A+B)^n-A^n\|=3^4-1$.

And $\|B\|\|A\|^{n-1}e^{\frac{\|B\|}{\|A\|}}=2e^2<3^4-1$.