Mister Exam

Graphing y = sqrt(log2(x))

v

The graph:

from to

Intersection points:

does show?

Piecewise:

The solution

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           ________
          / log(x) 
f(x) =   /  ------ 
       \/   log(2) 
$$f{\left(x \right)} = \sqrt{\frac{\log{\left(x \right)}}{\log{\left(2 \right)}}}$$
f = sqrt(log(x)/log(2))
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:
$$\sqrt{\frac{\log{\left(x \right)}}{\log{\left(2 \right)}}} = 0$$
Solve this equation
The points of intersection with the axis X:

Analytical solution
$$x_{1} = 1$$
Numerical solution
$$x_{1} = 1$$
The points of intersection with the Y axis coordinate
The graph crosses Y axis when x equals 0:
substitute x = 0 to sqrt(log(x)/log(2)).
$$\sqrt{\frac{\log{\left(0 \right)}}{\log{\left(2 \right)}}}$$
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
$$\frac{\frac{1}{\sqrt{\log{\left(2 \right)}}} \sqrt{\log{\left(x \right)}}}{2 x \log{\left(x \right)}} = 0$$
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
$$- \frac{2 + \frac{1}{\log{\left(x \right)}}}{4 x^{2} \sqrt{\log{\left(2 \right)}} \sqrt{\log{\left(x \right)}}} = 0$$
Solve this equation
The roots of this equation
$$x_{1} = e^{- \frac{1}{2}}$$

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:
Have no bends at the whole real axis
Horizontal asymptotes
Let’s find horizontal asymptotes with help of the limits of this function at x->+oo and x->-oo
$$\lim_{x \to -\infty} \sqrt{\frac{\log{\left(x \right)}}{\log{\left(2 \right)}}} = \infty$$
Let's take the limit
so,
horizontal asymptote on the left doesn’t exist
$$\lim_{x \to \infty} \sqrt{\frac{\log{\left(x \right)}}{\log{\left(2 \right)}}} = \infty$$
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 sqrt(log(x)/log(2)), divided by x at x->+oo and x ->-oo
$$\lim_{x \to -\infty}\left(\frac{\frac{1}{\sqrt{\log{\left(2 \right)}}} \sqrt{\log{\left(x \right)}}}{x}\right) = 0$$
Let's take the limit
so,
inclined coincides with the horizontal asymptote on the right
$$\lim_{x \to \infty}\left(\frac{\frac{1}{\sqrt{\log{\left(2 \right)}}} \sqrt{\log{\left(x \right)}}}{x}\right) = 0$$
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:
$$\sqrt{\frac{\log{\left(x \right)}}{\log{\left(2 \right)}}} = \frac{\sqrt{\log{\left(- x \right)}}}{\sqrt{\log{\left(2 \right)}}}$$
- No
$$\sqrt{\frac{\log{\left(x \right)}}{\log{\left(2 \right)}}} = - \frac{\sqrt{\log{\left(- x \right)}}}{\sqrt{\log{\left(2 \right)}}}$$
- No
so, the function
not is
neither even, nor odd
The graph
Graphing y = sqrt(log2(x))