An equation is a mathematical statement. It means:
1. Equality: For example, in the equation: 100=33+67, LHS is equal to RHS.
2. Dependence: For example, in the equation for a rectangular hyperbola: xy=1, each variable is dependent on the other.
3. A road map: For example, 4x+2(7-x)=20 shows itself how to solve it.
1). Remove brackets: 4x+14-2x=20
2). Combine like terms: 2x+14=20
3). Subtract 14 from both sides: 2x=6
4). Divide both sides by 2: x=3 You have the answer.
4. A story: For example, the equation mentioned at 3. tells a story: What is your story? Mine is: 7 people gathered around a bowl filled with 20 cookies. The bowl was empty when they left. Some people ate 4 cookies each, and the rest ate 2 each. How many people did eat 4 cookies?
In an equation, unknown variables are dealt with as if they were known quantities, so that full cast gathers in one place where a story develops.
5. There must be a lot of definitions.