# Laws of Logarithms HELP!

• Oct 10th 2012, 01:16 PM
Scottrich12
Laws of Logarithms HELP!
I need to use laws of logarithms methods to simplify and evaluate these equation

5n = 7 x 2n, rearrange and make n the subject

θ = 250 x e-0.05 x t and make t the subject

and continuing from that

what is the value of t when θ = 195C

I need log to the base 10 to be used preferably
• Oct 10th 2012, 01:21 PM
Plato
Re: Laws of Logarithms HELP!
Quote:

Originally Posted by Scottrich12
I need to use laws of logarithms methods to simplify and evaluate these equation

5n = 7 x 2n, rearrange and make n the subject

$\displaystyle n=\frac{\log_{10}(7)}{\log_{10}(5)-\log_{10}(2)}$
• Oct 10th 2012, 02:24 PM
Scottrich12
Re: Laws of Logarithms HELP!
That's the answer but how did you get it?
• Oct 10th 2012, 02:33 PM
Plato
Re: Laws of Logarithms HELP!
Quote:

Originally Posted by Scottrich12
That's the answer but how did you get it?

$\displaystyle \left( {\frac{5}{2}} \right)^n = 7$
• Oct 10th 2012, 02:36 PM
Scottrich12
Re: Laws of Logarithms HELP!
θ = 250 x e-0.05 x t and make t the subject

and continuing from that

what is the value of t when θ = 195◦C