數學解方程問題

you need to square both sides of the equation because the equation has square root on one or both sides, it is no method to solve the equation that has square root. As a result, the degree of the equation is higher. In accordance to the maths law, the n degree equation can produce at most n roots. Hence, the equation produce a double of root after the square process.

however, some roots may appear wrongly, because they just suit the equation after square but not before square. Therefore, the root that is not required should be rejected.

To prevent you will come out the wrong solution, you should check each root carelessly by putting back the root into the equation. If the root suits the original equation, it is the required root.