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how do i find 87= 21^x

 Feb 15, 2020
 #1
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+1

\(87= 21^x\\ ln87= ln21^x\\ ln87=x ln21\\ x=\frac{ln87}{ln21}\)

 

x= ln(87)/ln(21) = approx 1.4668665480402957

 
 Feb 15, 2020
 #2
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+1

 

Melody, is there a reason you used natural log?  I used log10 and got the same answer. 

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Guest Feb 15, 2020
 #3
avatar+107414 
+1

Hi Guest,

No there is no reason, you can use any log you want. 

Log 10 is an equally good alternative.  laugh

 
Melody  Feb 15, 2020, 9:01:19 PM
 #4
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Thank you, Melody.  I love the new avatar.  smiley  I looked it up; it's an actual road sign in Australia.

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Guest Feb 15, 2020, 9:27:15 PM
 #5
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Thanks guest,

Yes it is a relatively common roadside, in the country anyway. :)

 

I actually took a photo to use here but I cannot remember if this is my photo or a different one from the internet.

 
Melody  Feb 15, 2020, 10:29 PM
edited by Melody  Feb 15, 2020, 10:30 PM
edited by Melody  Feb 15, 2020, 10:31 PM

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