Question 979806
This is a quadratic equation if you 
write it like this:
{{{ ( e^x )^2 - 5*( e^x ) + 4 = 0 }}}
For now, I'll say: {{{ z = e^x }}}
{{{ z^2 - 5z + 4 = 0 }}}
By inspection:
{{{ ( z - 4 )*( z - 1 ) = 0 }}}
{{{ z = 4 }}}
{{{ z = 1 }}}
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{{{ z = e^x }}}
and
{{{ e^x = 4 }}}
{{{ x = ln(4) }}} ( larger value )
and
{{{ e^x = 1 }}}
{{{ x = ln(1) }}} ( smaller value )