66.1k views
2 votes
Ln(x+2)-ln(4x+3)=ln(1/2*x)

1 Answer

4 votes
ln(x+2)-ln(4x+3)=ln(1/2*x)

Using properties of logarithms


(ln(x+2))/(ln(4x+3)) = ln (x)/(2) \\ \\ (x+2)/(4x+3) = (x)/(2) \\ \\2(x+2)=x(4x+3) 2x+4=4x^2+3x \\ \\ 4 x^(2) +x-4=0 \\ \\ x= \frac{-b+/- \sqrt{b^(2)-4ac} }{2a} \\ \\ x= ( -1+/-√(1+64) )/(8) \\ \\ x_(1) = (-1+ √(65) )/(8) \\ \\ x_(2) = (-1- √(65) )/(8) Check: When you substitute x_(2) into \\ \\ ln(4x+3)=ln(4* (-1- √(65) )/(8) ) =ln( (-1- √(65) )/(2) ) you will get negative number under ln, that is impossible ,

so x2 is not a solution of this logarithmic equation.

Only x1 is a solution.


User Mkro
by
8.9k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories