Solving an exponential equation question 2

**math123456** · April 21st 2009, 07:30 PM

solve the exponential function:

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

**mr fantastic** · April 21st 2009, 07:33 PM

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.

**math123456** · April 21st 2009, 10:23 PM

How do you solve for x:

2^x = 8/35

**CaptainBlack** · April 21st 2009, 10:32 PM

Originally Posted by math123456

solve for x:

2^x = 8/35

Take logs:

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

and solve.

CB

**math123456** · April 22nd 2009, 11:49 AM

how would you answer that in exact form

**e^(i*pi)** · April 22nd 2009, 12:03 PM

Originally Posted by CaptainBlack

Take logs:

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

and solve.

CB

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:

Thread: Solving an exponential equation question 2