The Student Room Group
Reply 1
do you know the three log laws and the law to change base?

log(a) of x + log(a) of y = log(a) of xy
log(a) of x - log(a) of y = log(a) of x/y
n [log(a) of x] = log(a) of (x^n)

And change of base,

log(a) of x = [log(b) of x]/[log(b) of a]

Using these, you can solve that.
Reply 2
I know the rules, laws wotever but idon't know how to apply it in the context of the question
loga(x)=lnxlna\log_{a}(x) = \frac{\ln x}{\ln a}
logb(X)=lnXlnb\log_{b}(X) = \frac{\ln X}{\ln b}

yloga(x)zln(x2)12logb(X)=ylnxlnazln(x2)12lnXlnb=ln(xylna)ln([x2]z)ln(X12lnb) y\log_{a}(x) - z\ln(x^2) -12\log_{b}(X) = \\ y \frac{\ln x}{\ln a} - z \ln(x^{2}) - 12 \frac{\ln X}{\ln b} = \\\ln(x^{\frac{y}{\ln a}})-\ln([x^{2}]^{z}) - \ln (X^{\frac{12}{\ln b}})


Now use lnalnb=ln(ab)\ln a - \ln b = \ln (\frac{a}{b}) to tidy it up. I'd do it, but I've got to go.

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