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How do you solve the equation -3 equals 20log pharanthesis start X divide by 775 pharanthesis end?
MortenBrendefur
-3 = 20*log(x/775)
This is made difficult by the function 'log'
but lets start with what we easily can do.
Lets divide by 20 at both sides.
-3/20 = 20*log(x/775)/20 of which can be simplified into:
-3/20 = log(x/775)
Now for the fun part. We need to take log out, but how?
What is the inverse function of log? I'll just explain that one with a couple of examples.
10 to the power of log (9) = 9.
10 to the power of log (5) = 5.
It isn't that hard to understand really but I would not have thought of it myself if my calculator did not tell me.
Back to the equation. We have :
-3/20 = log(x/775)
We would like to take the function 'log' away on the right side and put it on the left side. By doing just that, we use the inverse function on both sides.
10^(-3/20)=10^(log(x/775)) of which turns into:
10^(-3/20)=x/775
Now to get rid of the number on the right side, we simply multiply on both sides.
10^(-3/20)*775=x/775*775 of which turns into:
10^(-3/20)*775=x
or it can be written like:
X=10^(-3/20)*775
Eqation solved.
++++
What was the origin of the question? It looks like a decibel calculation, though not in acoustics with such a high divisor.
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∙ 8y ago
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