2 points
*
Sure, let’s do it in base 3. 3 in base 3 is 10, and 3^(-1) is 10^(-1), so:
1/3 in base 10 = 1/10 in base 3
0.3… in base 10 = 0.1 in base 3
Multiply by 3 on both sides:
3 × 0.3… in base 10 = 10 × 0.1 in base 3
0.9… in base 10 = 1 in base 3.
But 1 in base 3 is also 1 in base 10, so:
0.9… in base 10 = 1 in base 10
-3 points
You’re having to use … to make your conversion again. If you need to to an irrational number to make your equation correct, it isn’t really correct.
4 points