Question

Which of the following is a solution of the compound inequality -1 < 2n + 1 < 5?

Answer 1

-1 < n < 5
n > 2 or n < -1
-1 < n < 2
n < -2 or n > 4

Answer 2

-1 < 2n +1 < 5
subtract 1 from all sides to get
-1 -1 < 2n+1-1 < 5-1
or
-2 < 2n < 4
divide 2 on all sides to get
-2/2 < 2n/2 < 4/2
or
-1 < n < 2

Answer 3

-1<2n+1<5
We want to isolate n:
So we want to Undo that addition and multiplication to get to n
But whatever we do to one side we must do to all others