Wednesday, April 25, 2012


If p is prime, which of the following could be prime?
I.  p+7
II. 4p^2-4p+1
III. p^2-p

(A) I only (B) II only (C) III only
(D) I,II,III (E) none

What KNOWLEDGE must middle/secondary students have to solve this? In what grade is this taught?

Ask students: If "could" was replaced by "must" would the answer change? Explain.

For homework, ask students to write their own version of this problem. You may get some awesome questions you can use later on!

Sent from my Verizon Wireless 4GLTE Phone


Jacob Antony said...

i think there a problem with this puzzle as well p^2-p is prime for p=2

Dave Marain said...

Jacob, I was more awake this am! You're right but that's why the answer is III only! Now what's your thought about 'could' vs 'must'?