SOLUTION: How do I solve this problem? Db=10log(5.3x10^-5/10^-16)

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Question 471160: How do I solve this problem?
Db=10log(5.3x10^-5/10^-16)

Found 2 solutions by Tatiana_Stebko, Theo:
Answer by Tatiana_Stebko(1539) About Me  (Show Source):
You can put this solution on YOUR website!

If you need more, have to use scientific calculator
10%28log%285.3%29%2B11%29=10%280.7243%2B11%29=117.243

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
I think your equation is as follows:
Db = 10*log((5.3 * 10^(-5))/(10^(-16))
Sticking that through the algebra.com formula generator, it would look like:
Db = 10%2Alog%28%285.3+%2A+10%5E%28-5%29%29%2F%2810%5E%28-16%29%29%29
Assuming that's your equation, then you would solve it as follows:
Db = 10%2Alog%28%285.3+%2A+10%5E%28-5%29%29%2F%2810%5E%28-16%29%29%29 is equivalent to:
Db = 10%2A%28log%28%285.3+%2A+10%5E%28-5%29%29+-+log%2810%5E%28-16%29%29%29%29 which is equivalent to:
Db = 10%2A%28log%285.3%29+%2B+log%2810%5E%28-5%29%29+-+log%2810%5E%28-16%29%29%29 which is equivalent to:
Db = 10%2A%28log%285.3%29+-5%2Alog%2810%29+%2B+16%2Alog%2810%29%29 which you can solve using your calculator to get:
Db = 10*(11.72427587) which equals 117.24237587.
I confirmed by using my calculator to solve the original equation.
Since that gave me the same answer as the final equation, I assumed the translation of the equation was correct.
The laws of logarithms that applied are:
First Law: log(a*b) = log(a) + log(b)
Second Law: log(a/b) = log(a) - log(b)
Third Law: log(a^b) = b*log(a)
In your problem, I could assign letters to each configuration to make it clearer.
Assume 5.3 equals a
Assume 10^(-5) = b
Assume 10^(-16) = c
Your equation then becomes:
Db = 10%2A%28log%28%28a%2Ab%29%29%2Fc%29
Use second law to get:
Db = 10%2A%28log%28%28a%2Ab%29%29+-+log%28c%29%29
Use first law to get:
Db = 10%2A%28log%28a%29+%2B+log%28b%29+-+log%28c%29%29
Since b = 10^(-5), we make b = d^e by making d = 10 and e = -5
Since c = 10^(-16), we make c = f^g by making f = 10 and g = -16
Our equation of:
Db = 10%2A%28log%28a%29+%2B+log%28b%29+-+log%28c%29%29 becomes:
Db = 10%2A%28log%28a%29+%2B+log%28d%5Ee%29+-+log%28f%5Eg%29%29
Now we use the third law to get:
Db = 10%2A%28log%28a%29+%2B+log%28d%5Ee%29+-+log%28f%5Eg%29%29 becomes:
Db = 10%2A%28log%28a%29+%2B+e%2Alog%28d%29+-+g%2Alog%28f%29%29
That becomes our final equation.
Since:
a = 5.3
e = -5
d = 10
g = -16
f = 10
substituting in our final equation, we get:
Db = 10%2A%28log%285.3%29+%2B+%28-5%29%2Alog%2810%29+-+%28-16%29%2Alog%2810%29%29
We simplify that to get:
Db = 10%2A%28log%285.3%29+-+5%2Alog%2810%29+%2B+16%2Alog%2810%29%29