# unknown equals constant or constant equals unknown?

Frequently, in solving a simple equation involving an unknown such as x + 1 = 2, at the end, we often write the answer as x = 1 instead of writing the answer as 1 = x, that is an unknown equals a constant (the unknown is put at the left side of the equation) insteads of a constant equal an unknown (the unknown is put at the right side of the equation). Is it wrong to write the answer as 1 = x with the unknown on the right side of the equation, that is a constant equal an unknown? why?

It's not wrong. It's just the way Yoda would write it. “One, $x$ is.”

It isn't wrong to write $1=x$ instead of $x=1$. They mean the same statement. However, in this statement $x$ is the subject so it should probably come first when you are describing it. Words in english are read from left to right so equations follow a similar pattern.

It is perfectly fine to write $1 = x$ as an alternative to $x = 1$.

Why can we do that?

Equality is an equivalence relation (on the real numbers, or any set of numbers), and it is thereby symmetric: "Symmetric" means that it is true that if $x = y$, then $y = x$. And, vice versa.

So either equation representing the solution to the posted problem is correct: they both assert precisely the same thing. Placing the variable to the left and its value to the right of the equal sign is mere "habit"/convention. Nothing more, nothing less.

• They must be using some reverse-Polish-notation. :-) +1 Sep 16, 2013 at 0:21
• Hahaha. Thanks, @Amzoti! Sep 16, 2013 at 0:28