Exponential and logarithmic equation assistance needed.

[LJay]

1.) ln x = 3 ? x

solving for x

so i know this is basically e^(3-x) = x
from there i'm absolutely lost
i've gotten 12 diff answers, all wrong

2.) x^3 ? x = logbase2 (x + 1)

solving for x

i set it up as 2^(x^3 - x) = (x + 1)
i've gotten a few diff answers as well but they're all wrong

any help would be appreciated, thanks!

 

[tkhunny]

How do you get any answer at all? They cannot be solved by elementary algebra. Simple as that.

Why do you believe you can solve them? The first one has a solution around x = 2¼, but you must use numerical methods to find it. Guess and check?

 

[LJay]

well both questions are part of my pre-calculus course's online homework component
would you mind showing me the method you used?

 

[Deleted member 4993]

1.) ln x = 3 ? x

solving for x

so i know this is basically e^(3-x) = x
from there i'm absolutely lost
i've gotten 12 diff answers, all wrong

2.) x^3 ? x = logbase2 (x + 1)

solving for x

i set it up as 2^(x^3 - x) = (x + 1)
i've gotten a few diff answers as well but they're all wrong
any help would be appreciated, thanks!

For a pre-calculus class, the acceptable method would be to plot y=ln(x) and ploty=3-x. Then find their points of intersection.

Similar method for second problem.

 

[LJay]

1.) ln x = 3 ? x

solving for x

so i know this is basically e^(3-x) = x
from there i'm absolutely lost
i've gotten 12 diff answers, all wrong

2.) x^3 ? x = logbase2 (x + 1)

solving for x

i set it up as 2^(x^3 - x) = (x + 1)
i've gotten a few diff answers as well but they're all wrong
any help would be appreciated, thanks!

For a pre-calculus class, the acceptable method would be to plot y=ln(x) and ploty=3-x. Then find their points of intersection.

Similar method for second problem.

thanks a lot!! saved my sanity
i knew it was something incredibly simple
wasted an embarrassing number of hours on these problems