# Solving an exponential equation question 2

• Apr 21st 2009, 08:30 PM
math123456
Solving an exponential equation question 2
solve the exponential function:

4(2^x) + 31(2^x) - 8 = 0
• Apr 21st 2009, 08:33 PM
mr fantastic
Quote:

Originally Posted by math123456
solve the exponential function:

4(2^x) + 31(2^x) - 8 = 0

It simplifies to $2^x = \frac{8}{35}$. Solve this.
• Apr 21st 2009, 11:23 PM
math123456
Solving an exponential equation question 2
How do you solve for x:

2^x = 8/35
• Apr 21st 2009, 11:32 PM
CaptainBlack
Quote:

Originally Posted by math123456
solve for x:

2^x = 8/35

Take logs:

$x \log(2)=\log(8/35)$

and solve.

CB
• Apr 22nd 2009, 12:49 PM
math123456
how would you answer that in exact form
• Apr 22nd 2009, 01:03 PM
e^(i*pi)
Quote:

Originally Posted by CaptainBlack
Take logs:

$x \log(2)=\log(8/35)$

and solve.

CB

Quote:

Originally Posted by math123456
how would you answer that in exact form

Divide through by log(2) to isolate it. The exact form will have log terms in it: