# Using properties of logarithms to compute

• May 15th 2013, 09:55 PM
curt26
Using properties of logarithms to compute
Given ln 2 = 0.6931 and ln 3 = 1.0986, use properties of logarithms to compute:

ln square root(8/27), Sorry I have no idea how to put a square root sign in.

Thank you very much
• May 15th 2013, 10:07 PM
MarkFL
Re: Using properties of logarithms to compute
Can you write the argument for the log function as a fraction involving only 2 and 3 raised to some power?
• May 27th 2013, 02:03 AM
ReneG
Re: Using properties of logarithms to compute
 img.top {vertical-align:15%;} $\ln{\sqrt{\frac{8}{27}}}$ Given img.top {vertical-align:15%;} $= \ln{\left\frac{8}{27}\right} ^\frac{1}{2}$ Equivalent fractional exponent img.top {vertical-align:15%;} $=\frac{\ln{\frac{8}{27}}}{2}$ Log property: img.top {vertical-align:15%;} $\log_b{a^n} = n\log_b{a}$ img.top {vertical-align:15%;} $=\frac{\ln{8} - \ln{27}}{2}$ Log property: img.top {vertical-align:15%;} $\log_b{\frac{a}{n}} = \log_b{a} - \log_b{n}$ img.top {vertical-align:15%;} $=\frac{\ln{2^3} - \ln{3^3}}{2}$ img.top {vertical-align:15%;} $8 = 2^3$ and img.top {vertical-align:15%;} $27 = 3^3$ img.top {vertical-align:15%;} $=\frac{3\ln{2} - 3\ln{3}}{2}$ Log property: img.top {vertical-align:15%;} $\log_b{a^n} = n\log_b{a}$ img.top {vertical-align:15%;} $=\frac{3(0.6931) - 3(1.0986)}{2}$ Substitute img.top {vertical-align:15%;} $\ln 2$ and img.top {vertical-align:15%;} $\ln 3$ img.top {vertical-align:15%;} $\approx -0.60825$ Simplify with calculator