Problem: If an integer n greater than 8 is a solution of the equation x2+ax+b=0 and the representation of a in the base n numeration system is 18, then the base n representation of b is
Answer Choices:
A. 18
B. 28
C. 80
D. 81
E. 280
Solution:
b=an−n2=(18)n​n−n2=(n+8)n−n2=(80)n​.