解く

1. Origins, structure, and basic meaning

• Structure: 解く(とく) means to solve a problem or undo something tied.
• Basic usage: It describes a teacher solving a difficult equation on the board.
  • 先生は難しい方程式を黒板で解いた。

2. Common pitfalls and similar expressions

• Solving and untying
  • 方程式を解く means finding a solution, while 靴ひもを解く means untying shoelaces.
• The connective form
  • The connective form of 解く is 解いて, and the past form is 解いた.