Expert: Paul Klarreich - 2/13/2011

Question
Hi I need help with a table that I cant find the rule for. I am in the IMP program book one. The coordinates are (1,2) (2,4) (3,7) (4,11) (5,16)(6,22). Please find a rule for these as soon as possible! I have had my dad look at it just have guessed and check and it is not coming out.

Answer
Questioner: Caleb Kraft
Country: United States
Category: Advanced Math
Private: No
Subject: Math Rule
Question: Hi I need help with a table that I cant find the rule for. I am in the IMP program book one. The coordinates are (1,2) (2,4) (3,7) (4,11) (5,16)(6,22). Please find a rule for these as soon as possible! I have had my dad look at it just have guessed and check and it is not coming out.

For your pairs:

(1,2) (2,4) (3,7) (4,11) (5,16)(6,22)

observe the differences in y's: (use Courier font)

(1,2)  (2,4) (3,7)  (4,11) (5,16) (6,22)
     2     3      4      5      6

So you should have a function whose differences are linear, so it should be a
quadratic:

y = ax^2 + bx + c

Now do substitution of 3 of your pairs and work it out.