恒等式

1. Origins, structure, and basic meaning

• Structure: 恒等式 is an equality whose two sides are equal for every value of the variables in the allowed domain.
• Basic usage: It is a mathematical noun used to describe a property of an expression or to prove that two sides are always equal.

2. Common pitfalls and similar expressions

• Distinguishing 方程式
  • 方程式 is associated with finding variable values that make an equation true. The key feature of 恒等式 is that it holds for all allowed values.
• Checking and proving
  • Checking a few substituted values differs from proving that an equality holds for every allowed value. 恒等式を証明する refers to the latter.