Which of the following variable names are INVALID in R? 1_variable variable_1 _variable variable@

1. Break Down the Problem

To determine which variable names are invalid in R, we need to analyze each given variable name based on R's variable naming rules. The options presented are:

1. 1_variable
2. variable_1
3. _variable
4. variable@

2. Relevant Concepts

In R, variable names must adhere to the following rules:

• Variable names must start with a letter (a-z, A-Z) or a dot (.) followed by a letter.
• After the initial character, variable names can include letters, numbers (0-9), dots, and underscores (_).
• Variable names cannot contain special characters like @, #, etc.
• Variable names cannot begin with a number.

3. Analysis and Detail

Now we'll analyze each variable name:

1. 1_variable: Starts with a number – INVALID.
2. variable_1: Starts with a letter and only contains letters and an underscore – VALID.
3. _variable: Starts with an underscore, which is allowed in R – VALID.
4. variable@: Contains the special character @ – INVALID.

4. Verify and Summarize

After analyzing each variable name according to R's naming conventions:

• Invalid Names: 1_variable, variable@
• Valid Names: variable_1, _variable

Final Answer

The INVALID variable names in R are 1_variable and variable@.