Posted by **Simon** on Friday, April 16, 2010 at 3:44am.

Logarithm!!!

Select all of the following that are true statements:

(a) log(2x) = log(2) + log(x)

(b) log(3x) = 3 log(x)

(c) log(12y) = 2 log(2) + log(3y)

(d) log(5y) = log(20y) – log(4)

(e) log(x) = log(5x) – log(5)

(f) ln(25) = 2ln(5)

(g) ln(1) = log(1)

(h) ln(e) = log(10)

(i) if y = e-3 then ln(3) = ey

(j) if log(x) = -12 then x = 1.00 x 10-12

(k) if ln(x) = -12 then x = 1.00 x 10-12

(l) none of these is correct

- math -
**Damon**, Friday, April 16, 2010 at 7:28am
type 1 log(xy) = log x + log y

type 2 log (x)^y = y log x

now look at a) type 1, true

b) not type 1, not type 2, false

in fact log 3x = log 3 + log x

c) type 1 and type 2

log (3*2^2* y) = log 3 + 2 log 2 + log y = log 3y + 2 log 2 true

d) type 1

log(20y/4) = log(20y) - log(4)

type 3 base^logbase(x) = x

g) ln(1) = log(1)

e^ln 1 = 1 = 10^log 1

ln 1 = 0 = log 1 true type 3

h) ln(e) = log(10) ?????????

e^lne = e so lne =1

also log 10=1

so true, type 3

i) y = e^-3 do not forget the ^ for exponent

ln y = -3 ln e

ln y = -3 not what you want

j) 10^log x = 10^-12

x = 10^-12 true but remember ^ sign for exponents !

k) e^ln x = x = e^-12 not 10^-12 false

- math -
**vyas pankaj**, Friday, March 27, 2015 at 7:44am
2 log 10 power 5 +log 10 power 8-1/2 log 10 power 4 answer

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