Logarithms Flashcards
y = logax is equal to
x=a^y
So log5(125)=3 is equal to
125 = 5^3
When adding logarithms with the same bass
The terms will be multiplied
Log5(2) + log5(4) =
Log5(8)
When taking away logarithms with the same bases
The terms will be divided (one taken away will be denominator)
Log5(8) - Log5(2) =
Log5(4)
Loga(x)^n=
nLoga(x)
Loga(1)=
0 since a^0=1
Loga(a) =
1 since a^1=a
Solving equations with unknown components
Take loge of both sides and calculate accordingly
e^x=7
loge(e)^x=loge(7)
x *1 = loge(7)
x=1.946
Graphing with logarithmic axis, y=ab^x
Take logs of both sides so (log will be whatever is in question) so (loge for example)loge(y)=loge(ab^x)
Then use log rules to get it to loge(y) = loge(b)*x +loge(a)
Now use y = mx + c equation to show what m = loge(b) and c = Loge(a) now solve both for a and b and put them into y =ab^x equation
Graphing with logarithmic axis, y=ax^b
Take logs of both sides (log will be whatever it is in question) so (loge for example)
Loge(y) =loge(ax^b)
Now solve using log rules to get Loge(y) = b*loge(x) + loge(a)
Now put y =mx +c equation below to show m=b and c = loge(a).
Solve both then find b and a, put these into original equation