Graphing y = log3(x+4)

You have entered [src]

       log(x + 4)
f(x) = ----------
         log(3)

f{\left(x \right)} = \frac{\log{\left(x + 4 \right)}}{\log{\left(3 \right)}}

f = log(x + 4)/log(3)

The graph of the function

The points of intersection with the X-axis coordinate

Graph of the function intersects the axis X at f = 0
so we need to solve the equation:

\frac{\log{\left(x + 4 \right)}}{\log{\left(3 \right)}} = 0

Solve this equation
The points of intersection with the axis X:

Analytical solution

x_{1} = -3

Numerical solution

x_{1} = -3

The points of intersection with the Y axis coordinate

The graph crosses Y axis when x equals 0:
substitute x = 0 to log(x + 4)/log(3).

\frac{\log{\left(4 \right)}}{\log{\left(3 \right)}}

The result:

f{\left(0 \right)} = \frac{\log{\left(4 \right)}}{\log{\left(3 \right)}}

The point:

(0, log(4)/log(3))

Extrema of the function

In order to find the extrema, we need to solve the equation

\frac{d}{d x} f{\left(x \right)} = 0

(the derivative equals zero),
and the roots of this equation are the extrema of this function:

\frac{d}{d x} f{\left(x \right)} =

\frac{1}{\left(x + 4\right) \log{\left(3 \right)}} = 0

Solve this equation
Solutions are not found,
function may have no extrema

Inflection points

Let's find the inflection points, we'll need to solve the equation for this

\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0

(the second derivative equals zero),
the roots of this equation will be the inflection points for the specified function graph:

\frac{d^{2}}{d x^{2}} f{\left(x \right)} =

- \frac{1}{\left(x + 4\right)^{2} \log{\left(3 \right)}} = 0

Solve this equation
Solutions are not found,
maybe, the function has no inflections

Horizontal asymptotes

Let’s find horizontal asymptotes with help of the limits of this function at x->+oo and x->-oo

\lim_{x \to -\infty}\left(\frac{\log{\left(x + 4 \right)}}{\log{\left(3 \right)}}\right) = \infty

Let's take the limit
so,
horizontal asymptote on the left doesn’t exist

\lim_{x \to \infty}\left(\frac{\log{\left(x + 4 \right)}}{\log{\left(3 \right)}}\right) = \infty

Let's take the limit
so,
horizontal asymptote on the right doesn’t exist

Inclined asymptotes

Inclined asymptote can be found by calculating the limit of log(x + 4)/log(3), divided by x at x->+oo and x ->-oo

\lim_{x \to -\infty}\left(\frac{\log{\left(x + 4 \right)}}{x \log{\left(3 \right)}}\right) = 0

Let's take the limit
so,
inclined coincides with the horizontal asymptote on the right

\lim_{x \to \infty}\left(\frac{\log{\left(x + 4 \right)}}{x \log{\left(3 \right)}}\right) = 0

Let's take the limit
so,
inclined coincides with the horizontal asymptote on the left

Even and odd functions

Let's check, whether the function even or odd by using relations f = f(-x) и f = -f(-x).
So, check:

\frac{\log{\left(x + 4 \right)}}{\log{\left(3 \right)}} = \frac{\log{\left(4 - x \right)}}{\log{\left(3 \right)}}

- No

\frac{\log{\left(x + 4 \right)}}{\log{\left(3 \right)}} = - \frac{\log{\left(4 - x \right)}}{\log{\left(3 \right)}}

- No
so, the function
not is
neither even, nor odd