![enter image description here](https://i.stack.imgur.com/7CC3U.jpg)

Ive seen example of : 

```
  int[] a1 = { 1, 2, 3 };
  int[] b1 = { 1, 2, 3 };

a1.Equals(b1) //false

a1.Equals(b1,EqualityComparer<int>.Default)); //true

```

However I cant get the overloaded method as you see...

what am i missing ?