Why do I get a cardview error when I run my project?

i get a source code in internet and i try to run it, but i get this error.((ERROR: Failed to resolve: cardview Affected Modules: app))how i can solve this error?
the following code is my build.gradle(madule:app), i try other version of library and update android studio even i try to delete every cardview in my project, but still have error.

apply plugin: 'com.android.application'

android {
    compileSdkVersion 29
    buildToolsVersion "30.0.1"
    defaultConfig {
        applicationId "com.example.ecommerce"
        minSdkVersion 23
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation "androidx.test.ext:junit:1.1.1"
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'

    implementation 'com.google.firebase:firebase-core:17.4.4'
    implementation 'com.google.firebase:firebase-database:19.3.1'
    implementation 'com.google.firebase:firebase-storage:19.1.1'
    implementation 'com.firebaseui:firebase-ui-database:3.2.2'
    implementation 'com.squareup.picasso:picasso:2.71828'
    implementation 'com.github.rey5137:material:1.2.5'
    //implementation 'com.android.support:cardview-v7:29.1.1'
    //implementation 'com.android.support:recyclerview-v7:29.1.1'
    implementation "androidx.cardview:cardview:1.0.0"
    implementation 'androidx.recyclerview:recyclerview:1.1.0'
    implementation 'io.paperdb:paperdb:2.6'
    implementation 'com.android.support:design:29.1.1'
    implementation 'de.hdodenhof:circleimageview:2.2.0'
    implementation 'com.theartofdev.edmodo:android-image-cropper:2.7.+'
    implementation 'com.cepheuen.elegant-number-button:lib:1.0.2'
    //implementation 'com.google.android.material:material:1.3.0-alpha01'
}

First:

You have to decide which dependencies of both Support Library or AndroidX you need in your application. You've added both Support Library and AndroidX dependencies to the project which is not correct.

Anyways, here is the right build.gradle after Migrate to AndroidX from Refactor menu:

implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'com.google.firebase:firebase-core:17.4.4'
implementation 'com.google.firebase:firebase-database:19.3.1'
implementation 'com.google.firebase:firebase-storage:19.1.1'
implementation 'com.firebaseui:firebase-ui-database:3.2.2'
implementation 'com.squareup.picasso:picasso:2.71828'
implementation 'com.github.rey5137:material:1.2.5'
implementation "androidx.cardview:cardview:1.0.0"
implementation 'androidx.recyclerview:recyclerview:1.1.0'
implementation 'io.paperdb:paperdb:2.6'
implementation 'com.google.android.material:material:1.1.0'
implementation 'de.hdodenhof:circleimageview:3.1.0'
implementation 'com.theartofdev.edmodo:android-image-cropper:2.7.0'
implementation 'com.cepheuen.elegant-number-button:lib:1.0.2'

Second:

> ((ERROR: Failed to resolve: cardview Affected Modules: app)

This is because it cannot download the needed libraries from maven or any other repositories which is mostly caused by your IP limitations.