已知函数$f\left(x\right)=(1-\frac{a}{x})e^x$，若同时满足条件：
①$\exists x_0\in (0,+\infty ),x_0$为f(x)的一个极大值点；
②$\forall x\in (8,+\infty ),$f(x)>0，.则实数a的取值范围是（    ）

A: ____do you make a chicken sandwich?

B:____, put the yogurt on a slice of bread.

A: And then?

B: Cut up an onion and a tomato. Add these____the sandwich.

A: What do you do next?

B:____some lettuce and the chicken slices on the sandwich. Put the relish on the chicken.

A: And ____, put another slice of bread on the top.

B: Yes, you are right.

若$x^2+m^{2}xy+64y^2$是一个完全平方式，则m的值为（   ）