SOLUTION: Please help me solve this equation. {{{lnx + ln(x+1)=2}}}. I tried bringing the foil method bringing {{{(x+1)}}} with {{{lnx}}}, but all I ended up with was {{{ln x^3=2}}} and my t

Question 78142: Please help me solve this equation. . I tried bringing the foil method bringing with , but all I ended up with was and my teacher said that my steps were wrong. Can you help me to find out where it is exactly I went wrong.
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
You cannot foil these parenthesis, you must use logarithmic identities to solve

Use the identity:
Distribute
Raise both sides to exponents with the base of e. This undoes the natural log

Subtract from both sides
Since e^2 is approximately 7.3891 we can say

Now use the quadratic formula:

Solved by pluggable solver: SOLVE quadratic equation with variable

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=30.5564 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 2.26389218313595, -3.26389218313595. Here's your graph:

So our answer is
or
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