Mister Exam

Graphing y = ln(tg3x)

v

The graph:

from to

Intersection points:

does show?

Piecewise:

The solution

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f(x) = log(tan(3*x))
$$f{\left(x \right)} = \log{\left(\tan{\left(3 x \right)} \right)}$$
f = log(tan(3*x))
The graph of the function
The points of intersection with the Y axis coordinate
The graph crosses Y axis when x equals 0:
substitute x = 0 to log(tan(3*x)).
$$\log{\left(\tan{\left(0 \cdot 3 \right)} \right)}$$
The result:
$$f{\left(0 \right)} = \tilde{\infty}$$
sof doesn't intersect Y
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:
$$\frac{d}{d x} f{\left(x \right)} = $$
the first derivative
$$\frac{3 \tan^{2}{\left(3 x \right)} + 3}{\tan{\left(3 x \right)}} = 0$$
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:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
the second derivative
$$9 \left(- \frac{\left(\tan^{2}{\left(3 x \right)} + 1\right)^{2}}{\tan^{2}{\left(3 x \right)}} + 2 \tan^{2}{\left(3 x \right)} + 2\right) = 0$$
Solve this equation
The roots of this equation
$$x_{1} = - \frac{\pi}{12}$$
$$x_{2} = \frac{\pi}{12}$$

Сonvexity and concavity intervals:
Let’s find the intervals where the function is convex or concave, for this look at the behaviour of the function at the inflection points:
Concave at the intervals
$$\left(-\infty, - \frac{\pi}{12}\right] \cup \left[\frac{\pi}{12}, \infty\right)$$
Convex at the intervals
$$\left[- \frac{\pi}{12}, \frac{\pi}{12}\right]$$
Horizontal asymptotes
Let’s find horizontal asymptotes with help of the limits of this function at x->+oo and x->-oo
True

Let's take the limit
so,
equation of the horizontal asymptote on the left:
$$y = \lim_{x \to -\infty} \log{\left(\tan{\left(3 x \right)} \right)}$$
True

Let's take the limit
so,
equation of the horizontal asymptote on the right:
$$y = \lim_{x \to \infty} \log{\left(\tan{\left(3 x \right)} \right)}$$
Inclined asymptotes
Inclined asymptote can be found by calculating the limit of log(tan(3*x)), divided by x at x->+oo and x ->-oo
True

Let's take the limit
so,
inclined asymptote equation on the left:
$$y = x \lim_{x \to -\infty}\left(\frac{\log{\left(\tan{\left(3 x \right)} \right)}}{x}\right)$$
True

Let's take the limit
so,
inclined asymptote equation on the right:
$$y = x \lim_{x \to \infty}\left(\frac{\log{\left(\tan{\left(3 x \right)} \right)}}{x}\right)$$
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:
$$\log{\left(\tan{\left(3 x \right)} \right)} = \log{\left(- \tan{\left(3 x \right)} \right)}$$
- No
$$\log{\left(\tan{\left(3 x \right)} \right)} = - \log{\left(- \tan{\left(3 x \right)} \right)}$$
- No
so, the function
not is
neither even, nor odd