refactor(math):refact ApproxRoot for readality

[xujiangyu]

Description

Closes: #XXXX

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• [ ] reviewed state machine logic, API design and naming, documentation is accurate, tests and test coverage

Summary by CodeRabbit

• New Features

  • Enhanced the ApproxRoot method to handle zero as a root parameter, improving calculation accuracy.

• Bug Fixes

  • Simplified logic for root calculation, ensuring clearer handling of base cases and negative inputs.

• Documentation

  • Updated comments for better clarity on the method's functionality and logic.