Question

When solving 2|x + 1| − 1 = 11 one student decided to solve the equation by first solving 2y − 1 = 11. What must have been his substitution?

Answer 1

So here we have 2 equations:

2|x+1| - 1 = 11 and 2y - 1 = 11

Well, if you compare these two equations, you can notice that the |x+1| have been substituted by the variable y. So the student considered that y = |x+1|.

Hope this helps! :)