Error:(27, 13) Failed to resolve: com.google.firebase:firebase-core:9.8.0
<p>I'm trying to use Firebase in my app. </p>

<p>After adding three lines to Gradle, I get this error:</p>

<blockquote>
  <p>Error:(27, 13) Failed to resolve: com.google.firebase:firebase-core:9.8.0</p>
</blockquote>

<p>Here are some images of my code:</p>

<p><a href="https://i.stack.imgur.com/X0Uqy.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/X0Uqy.png" alt="this is in the application Gradle "></a>
<a href="https://i.stack.imgur.com/1M9bC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1M9bC.png" alt="this is something else"></a>
<a href="https://i.stack.imgur.com/TUODy.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TUODy.png" alt="this is in the application Gradle"></a></p>

<p>Why am I getting this error?</p>