How do you find the derivative of log_(3)x?

1 Answer
Mar 15, 2016

frac{"d"}{"d"x}(log_3(x)) = 1/(xln(3)).

Explanation:

There is an identity that states

log_a(b) = frac{ln(a)}{ln(b)},

for a > 0 and b > 0.

So, we can write

log_3(x) = ln(x)/ln(3)

for x > 0.

So to find the derivative, it helps if you know that

frac{"d"}{"d"x}(ln(x)) = 1/x.

So,

frac{"d"}{"d"x}(log_3(x)) = frac{"d"}{"d"x}(ln(x)/ln(3))

= 1/ln(3) frac{"d"}{"d"x}(ln(x))

= 1/(xln(3)).