Question

For `6x+9 = 6x + a`, what is the value of `a` such that there's infinitely many solutions?

Answer 1

`9`

Explanation:

If a were any other answer, they wouldn't be equal anymore. If a were `9` however, `x` could be anything and both sides would be the same.

For example. If we put `9` for `a`, and then `1` for `x`, our equation would be `15 = 15`. This is a sort of circular equation because it is stating the obvious and not getting you anywhere, but it shows that whatever you put for `x` one side will force you to getting the same answer on the other side.

Therefore, if `a = 9`, there would be infinitely many solutions.