Query about question "$1 + x + x^2 = 1 + 9 + 9^2$..." [9042]

GRE GRE Quant Problem Solving
1

https://www.gregmat.com/problems/quant?problem=1-x-x2-1-9-92

write your question here… Would x=9 not also work here?

2

It does, indeed.