If 125

_{x}= 20_{10}find x-
**A.**

2 -
**B.**

3 -
**C.**

4 -
**D.**

5

##### Correct Answer: Option B

##### Explanation

125_{x} = 20

1x*X*^{2} + 2x*X*^{1} + 5x*X*^{0} = 20*X*^{2} + 2*X* + 5 = 20*X*^{2} + 2*X* – 15 = 0

(*X* + 5)( *X* – 3) = 0*X* + 5 implies *X* = -5*X* – 3 implies *X* = 3

But *X* cannot be negative

∴*X* = 3