2023 AMC 12B Problems/Problem 12
Problem
For complex number 
and 
(where 
), define the binary operation
$u \ding{39} v = ac + bdi$ (Error compiling LaTeX. Unknown error_msg)
Suppose 
is a complex number such that $z\din{39} z = z^{2}+40$ (Error compiling LaTeX. Unknown error_msg). What is 
?
