Showing position by using TextMesh

Hi . This code doesn't work ;/ Why ? Can someone tell me what is bad ?

 using UnityEngine;
 using System.Collections;
 
 public class Pozycja : MonoBehaviour {
 
     Vector3 pos = transform.position.x;
     
     // Update is called once per frame
     void FixedUpdate () {
         transform.GetComponent(TextMesh) = "" + pos;
     }
 }