Equivalent quadratic expressions
Numeric surprises

The three series of equalities below present two different calculations leading to the same result:

0*2=1²-1
1*3=2²-1
2*4=3²-1
3*5=4²-1
...
0*1=(1²-1)/4
1*2=(3²-1)/4
2*3=(5²-1)/4
3*4=(7²-1)/4
...
0²+1²=(1²+1)/2
1²+2²=(3²+1)/2
2²+3²=(5²+1)/2
3²+4²=(7²+1)/2
...


Formulate the three phenomena using six correspondence rules. Do the correspondence rules help you explain the "surprises"?
  • Invent other series of numerical equalities that show similar phenomena.








  • Vertex Form
    Polynomial Form
    Product Form

    Reading information about functions
    Immunization against the common cold
    Numeric surprises
    Constructing functions
    Wage increase
    Partial pictures
    Examining value tables
    Families of functions
    Vertex paths
    Family and sub-families
    Parametric families

    Exercise 1
    Exercise 2
    Exercise 3
    Exercise 4
    Exercise 5
    Exercise 6
    Exercise 7
    Exercise 8
    Exercise 9
    Exercise 10
    Exercise 11
    Exercise 12