Inx In 9x 2 4SolutionGiven in question ln x lnx2 4 usin
Solution
Given in question
ln x + ln(x+2) = 4
using property ln(A) +ln (B) = ln(AB)
we get
ln (x(x+2)) =4
or
x2+2x = e4
x2+2x-e4=0
applying solution for ax2 +bx +c=0
here, a=1,b=2,c=-e4
so
x1=(-b+(b2-4ac)1/2)/2a
and, x2 =(-b-(b2-4ac)1/2)/2a
putting above values we get
x1=-1+(1+e4)1/2
x2=-1-(1+e4)1/2
x2 cannot be the solution as, log values cant be negative so, neglecting x2
we get only one solution -1+(1+e4)1/2
x=8.910.....ans.
