DireBaseDataBase in a Fragment

my problem is that when trying to use the method "FirebaseDatabase" in a fragment, Android studio does not solve it.

I am new to this, I wanted to know if someone can help me.

Fragment

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.firebase.database.FirebaseDatabase;

public class tap2tips  extends Fragment {
    RecyclerView mRecyclerView;
    FirebaseDataBase mFirebaseDataBase;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.tap2tips, container, false);
        return rootView;
    }
}