# [SOLVED] Simultaneous equations

• Jan 31st 2009, 11:54 PM
requal
[SOLVED] Simultaneous equations
Solve \$\displaystyle 2^x=14-2x\$ simultaneously.
• Jan 31st 2009, 11:59 PM
red_dog
A solution is \$\displaystyle x=3\$.

Let \$\displaystyle f(x)=2^x, \ g(x)=14-2x\$

\$\displaystyle f(x)\$ is strictly increasing, and \$\displaystyle g(x)\$ is strictly decreasing, so the solution is unique.
• Feb 1st 2009, 12:02 AM
Jhevon
Quote:

Originally Posted by requal
Solve \$\displaystyle 2^x=14-2x\$ simultaneously.

this is not really simultaneous equation problem. you need more than one equation for that.

note that on the right, if you make x too big (bigger than 7), you get a negative answer. the left side is always positive, so you want to try x values that are less than 7. there is one positive solution (meaning you would try integer values for x). trial and error can find it
• Feb 1st 2009, 12:10 AM
Moo
Quote:

Originally Posted by Jhevon
this is not really simultaneous equation problem. you need more than one equation for that.

note that on the right, if you make x too big (bigger than 7), you get a negative answer. the right side is always positive, so you want to try x values that are less than 7. there is one positive solution (meaning you would try integer values for x). trial and error can find it

Got any problem with left & right ? :D

(Bear)

*runs fast*