In the fourth grade, I studied equations. Equation refers to an equation with unknown numbers, which represents the equal relationship between two mathematical formulas (such as two numbers, functions, quantities and operations). The value of the unknown that makes the equation hold is called "solution" or "root". The process of finding the solution of the equation is called "solving the equation". By solving the equation, the difficulty of reverse thinking can be avoided, and the equation containing the quantity to be solved can be directly put forward. The equation has many forms, such as one-dimensional linear equation, two-dimensional linear equation, one-dimensional quadratic equation and so on. , or it can be composed of equations to solve multiple unknowns.