Posted by Joe on .
When solving 5x^250x+125=0, a space alien got x=8 for one of the two roots. What possible base could the alien be using? (Note: the coefficients are also in this base. That is 5,50,125 are all in this mystery base as well)

Intro to Computer Engineering 
Steve,
5*8^2  5b(8) + b^2+2b+5 = 0
b^2 38b + 325 = 0
b = 13,25
check:
base 13
5*8*8 = 328
50*8 = 520
125 = 200
328520+200 = 0
base 25
5*8*8 = 0 12 20 (base 25)
125 = 1 2 5
add: 1 15 0
50*8 = 1 15 0
subtract: 0