Question 810322
{{{ log( x+4 ) + log( x ) = 9 }}}
Make the substitution:
{{{ 9 = log( 10^9 ) }}} 
{{{ log( x+4 ) + log( x ) = log( 10^9 ) }}}
{{{ log( (x+4)*x ) = log( 10^9 ) }}}
{{{ ( x+4 )*x = 10^9 }}}
{{{ x^2 + 4x - 10^9 }}}
Use quadratic formula
{{{ x = (-b +- sqrt( b^2 - 4*a*c )) / (2*a) }}}
{{{ a = 1 }}}
{{{ b = 4 }}}
{{{ c = -10^9 }}}
{{{ x = (-4 +- sqrt( 4^2 - 4*1*(-10^9 ))) / (2*1) }}}
{{{ x = (-4 +- sqrt( 16 + 4000000000 )) / 2 }}}
The answer looks pretty strange. I
think my method is OK, but the results
are a little odd
I would get another opinion