# Finding roots of an exponential equation with multiple base numbers

• Apr 22nd 2009, 09:19 PM
jvigar
Finding roots of an exponential equation with multiple base numbers
Hey everyone, first post.

Just wondering if anyone can help me out with finding 'a' when the equation below is equal to 0

[IMG]file:///C:/Users/Jaiba/AppData/Local/Temp/moz-screenshot-2.jpg[/IMG][IMG]file:///C:/Users/Jaiba/AppData/Local/Temp/moz-screenshot-3.jpg[/IMG](94-10^a)*10^a*ln10+(118-16^a)*16^a*ln16+(147-25^a)*25^a*ln25+(180-40^a)*40^a*ln40+(230-60^a)*60^a*ln60

Cheers
[IMG]file:///C:/Users/Jaiba/AppData/Local/Temp/moz-screenshot.jpg[/IMG][IMG]file:///C:/Users/Jaiba/AppData/Local/Temp/moz-screenshot-1.jpg[/IMG]
• Apr 22nd 2009, 09:32 PM
Quote:

Originally Posted by jvigar
Hey everyone, first post.

Just wondering if anyone can help me out with finding 'a' when the equation below is equal to 0

[IMG]file:///C:/Users/Jaiba/AppData/Local/Temp/moz-screenshot-2.jpg[/IMG]

[IMG]file:///C:/Users/Jaiba/AppData/Local/Temp/moz-screenshot-3.jpg[/IMG]

(94-10^a)*10^a*ln10+(118-16^a)*16^a*ln16+(147-25^a)*25^a*ln25+(180-40^a)*40^a*ln40+(230-60^a)*60^a*ln60

Cheers
[IMG]file:///C:/Users/Jaiba/AppData/Local/Temp/moz-screenshot.jpg[/IMG]

[IMG]file:///C:/Users/Jaiba/AppData/Local/Temp/moz-screenshot-1.jpg[/IMG]

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• Apr 23rd 2009, 02:54 AM
jvigar
sorry about that, I tried to paste directly from maple.

The equation is,

(94-10^a)*10^a*ln10+(118-16^a)*16^a*ln16+(147-25^a)*25^a*ln25+(180-40^a)*40^a*ln40+(230-60^a)*60^a*ln60 = 0

and I'm trying to find "a"

many thanks

Josh
• Apr 23rd 2009, 03:29 AM
CaptainBlack
Quote:

Originally Posted by jvigar
sorry about that, I tried to paste directly from maple.

The equation is,

(94-10^a)*10^a*ln10+(118-16^a)*16^a*ln16+(147-25^a)*25^a*ln25+(180-40^a)*40^a*ln40+(230-60^a)*60^a*ln60 = 0

and I'm trying to find "a"

many thanks

Josh

Ask Maple for a numerical solution. It should give a ~= 1.3674 for the positive root (I have not checked for negative roots)

(you can't link to image files on your hard drive, they have to be on a machine that can been seen by the internet (such as an image hosting server), otherwise upload the image from the attachments dialog in the advanced editor)

CB
• Apr 23rd 2009, 04:59 AM
jvigar
Thanks, I must have done something wrong in maple.

I ended up using newtons method in excel, and got the same value.

Thanks again for all your help

Josh