MathDB

In maths class Albrecht had to compute

(a+2b-3)^2

. His result was

a^2 +4b^2-9

. ‘This is not correct’ said his teacher, ‘try substituting positive integers for

a

and

b

.’ Albrecht did so, but his result proved to be correct. What numbers could he substitute? a) Show a good substitution. b) Give all the pairs that Albrecht could substitute and prove that there are no more.

Problem Statement