Why am I getting error CS1525 when I use the question mark symbol?

I am very new to unity and have been following some tutorials to learn and to try to make a simple game. I followed this tutorial video to make a simple pong game. Here’s my code:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Ball : MonoBehaviour
{

public float speed = 5f;

// Start is called before the first frame update
void Start()
{
    float sx = Random.Range(0, 2) == ? -1 : 1;
    float sy = Random.Range(0, 2) == ? -1 : 1;

    GetComponent<Rigidbody>().velocity = new Vector3(speed * sx, speed * sy, 0f);
}

// Update is called once per frame
void Update()
{
    
}

The problem is that in the lines that say
float sx = Random.Range(0, 2) == ? -1 : 1;
and

float sy = Random.Range(0, 2) == ? -1 : 1;

the question marks in them are both marked with red squiggles underneath them and say CS1525 invalid expression term “?” when I hover over them. Also, this is in Visual Studio for Mac. Does anyone know how to fix this? Thanks in advance!

Oops. Sorry about this. I did more research and tried checking my code against the video again, and I just had a typo!