This applet allow the teacher to show quickly to students why -(n+3)/3 not equal to (-n+3)/3
And also shows -((n+3)/3) =-(n+3)/3 = (-n-3)/3 = (n+3)/(-3).
The concept of equivalence can be illustrated by the fact that no matter what value of x is substituted (using the slider n) the values on the left and on the right are equal if the expressions are equivalent.
