Solving for unknown exponents

  • Thread starter foxyman20
  • Start date
  • #1
2
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Ok i know this should be a relatively simple equation but i haven't done this stuff in so long i can't remember how to solve it. here goes.

4^(x+2) = 7^x +681

Solve for x

I know the answer is 3 from simple trial and error but i can't show the work to prove it and i know that harder problems exist so i would like to know the procedure. I'm pretty sure that either logs or natural logs (LN) is required somehow. Any help would be greatly appreciated.

Thanks.
 

Answers and Replies

  • #2
2
0
well i figure the physics people should have no problem with this.

Ok i know this should be a relatively simple equation but i haven't done this stuff in so long i can't remember how to solve it. here goes.

4^(x+2) = 7^x +681

Solve for x

I know the answer is 3 from simple trial and error but i can't show the work to prove it and i know that harder problems exist so i would like to know the procedure. I'm pretty sure that either logs or natural logs (LN) is required somehow. Any help would be greatly appreciated.

Thanks.
 
  • #3
olgranpappy
Homework Helper
1,271
3
there's no easy way to solve an equation that has a polynomial on one side and a transcendental function on the other. Sorry.

P.S. there is another solution near 4.8622 too, but no other solutions besides that one.
 

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