Android studio where is gradle.properties file?

I'm trying to generate a signed apk but I always get the same error.

To run dex in process, the Gradle daemon needs a larger heap.
It currently has approximately 910 MB.
For faster builds, increase the maximum heap size for the Gradle daemon to more than 2048 MB.
To do this set org.gradle.jvmargs=-Xmx2048M in the project gradle.properties.

I can´t file that file but I tried modify gradle-wrapper.properties but I still get the same error.

This is my gradle-wrapper.properties file

#Thu May 05 20:51:44 CEST 2016
distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists
org.gradle.jvmargs=-Xmx2048m

I have already try too Android Gradle Could not reserve enough space for object heap

Just create a file called gradle.properties in your root project:

root
|--gradle.properties
|--build.gradle
|--settings.gradle
|--app
|----build.gradle

Then add inside the file:

org.gradle.jvmargs=-Xmx2048m

In the Project window, right click your Project name and choose New > File. The new file name is "gradle.properties". The content is: org.gradle.jvmargs=-Xmx1536M ;(or the number shown in your Gradle Console) in a line like this: ... increase the maximum heap size for the Gradle daemon to more than 2048 MB.

gradle.properties is located in windows

    C:\Users\<%User_Name%>\.gradle\gradle.properties

In android studio

   `Gradle Scripts` >> `gradle.properties (Global Properties)`

Just follow the below steps:

1)Go to File
2)Create a New File
3)Name it as gradle.properties
4)Write the content in the file 
For eg:
 org.gradle.jvmargs=-Xmx1536M;(replace it with the numbers in your gradle file)

Hope it helps.