Lg (x^2 - 4) = lg 5

Question

I have to find x! Can you help me 

lg= logarithm

Answer 1

Lg is NOT a standard abbreviation for "logarithm"

 

Two common abbreviations are log (for log₁₀) and ln (for log_e).

 

In any event, whatever base you intended, this logarithmic equation can be converted to

x²-4 = 5 by the act of raising the base to the stated logarithms (since logarithms are exponents).

This serves to eliminate Lg and now you have an easy equation to solve for x.