Posted by **Sunny** on Wednesday, January 4, 2012 at 5:18am.

Solve the exponential equation. Express your solutions in exact form only. Please show all of your work.

3^x-70*3^-x=9

- college algebra -
**Reiny**, Wednesday, January 4, 2012 at 8:20am
multiply each term by 3^x

3^(2x) - 70 = 9(3^x)

(3^x)^2 - 9(3^x) - 70=0

let 3^x = y , our equation becomes

y^2 - 9y - 70 = 0

(y-14)(y+5) = 0

y = 14 or y = -5

then

3^x = 14

log (3^x) = log14

xlog3 = log14

**x = log14/log3 or appr. 2.402**

or e^x = -5, which has no solution.

## Answer this Question

## Related Questions

- Math - Exponential equation - Solve the exponential equation. Express your ...
- Math - 2 - Solve the exponential equation. Express your solutions in exact form ...
- pre calculus - Solve the exponential equation Express you solutions in exact ...
- College Algebra - Solve the logarithmic equation. Express your solutions in ...
- precalculus - solve the exponential equation express in exact form only show all...
- Math - Solve the logarithmic equation. Express your solutions in exact form only...
- college algebra--I really need help!! - solve the following exponential equation...
- algebra - solve the exponential equation Express in exact form. 5e^xlog_9 = 11 ...
- college algebra - 1. find the equation of the line with the given properties. ...
- precalculus - Solve the logarithmic equation. Express your solutions in exact ...

More Related Questions