How Do You Solve ln x + ln(x+1) = 7?

[vt33]

Can anyone help me with this natural log?

ln x + ln(x+1) = 7

I've tried putting it in quadratic form but all I get is x^2 + x - 7=0
which doesn't seem to factor. What am I doing wrong?

 

[geometer]

Can anyone help me with this natural log?

ln x + ln(x+1) = 7

I've tried putting it in quadratic form but all I get is x^2 + x - 7=0
which doesn't seem to factor. What am I doing wrong?

For one thing, your equation is wrong. It should be x^2 + x - e^7 = 0

Second, there are methods other than factoring for solving quadratic equations.

 

[vt33]

I've never seen this

well, thanks but, I've never actually seen this type of equation. What do I do with the -e^7, or what I mean is how do I factor that? Actually, should I just use the quadratic formula?

 

[geometer]

well, thanks but, I've never actually seen this type of equation. What do I do with the -e^7, or what I mean is how do I factor that? Actually, should I just use the quadratic formula?

Your calculator should be able to give you a value for e^7. I am assuming that you know what e is. Then, using the quadratic formula should give you the correct answer.

 

[vt33]

thanks!

I see what you mean now, so I'll go crunch the numbers! Thanks a lot :)