If 2x^2 + 8y = 1215 and x^2 + 8y = 1215, what is the value of x?

To solve for x given the equations 2x² + 8y = 1215 and x² + 8y = 1215, we first notice that both equations share the term 8y, which allows us to manipulate the equations effectively.

1. **Isolate 8y**: From the second equation, we can isolate 8y:

x² + 8y = 1215 can be rewritten as 8y = 1215 – x².

2. **Substituting 8y**: Now, we substitute this expression for 8y into the first equation:

2x² + (1215 – x²) = 1215

3. **Simplifying the equation**: Simplifying gives us:

2x² – x² + 1215 = 1215

or x² = 0.

4. **Solving for x**: Since x² = 0, we find that:

x = 0.

5. **Conclusion**: Therefore, the value of x when both equations hold true is 0.