Mister Exam

Graphing y = ctg((x+1)/2)

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The graph:

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Intersection points:

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Piecewise:

The solution

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          /x + 1\
f(x) = cot|-----|
          \  2  /
f(x)=cot(x+12)f{\left(x \right)} = \cot{\left(\frac{x + 1}{2} \right)}
f = cot((x + 1)/2)
The graph of the function
02468-8-6-4-2-1010-1000500
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:
cot(x+12)=0\cot{\left(\frac{x + 1}{2} \right)} = 0
Solve this equation
The points of intersection with the axis X:

Analytical solution
x1=1+πx_{1} = -1 + \pi
Numerical solution
x1=77.5398163397448x_{1} = 77.5398163397448
x2=96.3893722612836x_{2} = 96.3893722612836
x3=54.4070751110265x_{3} = -54.4070751110265
x4=71.2566310325652x_{4} = 71.2566310325652
x5=60.6902604182061x_{5} = -60.6902604182061
x6=39.8407044966673x_{6} = 39.8407044966673
x7=85.8230016469244x_{7} = -85.8230016469244
x8=79.5398163397448x_{8} = -79.5398163397448
x9=102.672557568463x_{9} = 102.672557568463
x10=10.4247779607694x_{10} = -10.4247779607694
x11=35.5575191894877x_{11} = -35.5575191894877
x12=90.106186954104x_{12} = 90.106186954104
x13=48.1238898038469x_{13} = -48.1238898038469
x14=64.9734457253857x_{14} = 64.9734457253857
x15=73.2566310325652x_{15} = -73.2566310325652
x16=29.2743338823081x_{16} = -29.2743338823081
x17=58.6902604182061x_{17} = 58.6902604182061
x18=8.42477796076938x_{18} = 8.42477796076938
x19=98.3893722612836x_{19} = -98.3893722612836
x20=52.4070751110265x_{20} = 52.4070751110265
x21=22.9911485751286x_{21} = -22.9911485751286
x22=46.1238898038469x_{22} = 46.1238898038469
x23=2.14159265358979x_{23} = 2.14159265358979
x24=66.9734457253857x_{24} = -66.9734457253857
x25=16.707963267949x_{25} = -16.707963267949
x26=92.106186954104x_{26} = -92.106186954104
x27=41.8407044966673x_{27} = -41.8407044966673
x28=83.8230016469244x_{28} = 83.8230016469244
x29=27.2743338823081x_{29} = 27.2743338823081
x30=14.707963267949x_{30} = 14.707963267949
x31=20.9911485751286x_{31} = 20.9911485751286
x32=4.14159265358979x_{32} = -4.14159265358979
x33=33.5575191894877x_{33} = 33.5575191894877
The points of intersection with the Y axis coordinate
The graph crosses Y axis when x equals 0:
substitute x = 0 to cot((x + 1)/2).
cot(12)\cot{\left(\frac{1}{2} \right)}
The result:
f(0)=cot(12)f{\left(0 \right)} = \cot{\left(\frac{1}{2} \right)}
The point:
(0, cot(1/2))
Extrema of the function
In order to find the extrema, we need to solve the equation
ddxf(x)=0\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:
ddxf(x)=\frac{d}{d x} f{\left(x \right)} =
the first derivative
cot2(x+12)212=0- \frac{\cot^{2}{\left(\frac{x + 1}{2} \right)}}{2} - \frac{1}{2} = 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
d2dx2f(x)=0\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:
d2dx2f(x)=\frac{d^{2}}{d x^{2}} f{\left(x \right)} =
the second derivative
(cot2(x+12)+1)cot(x+12)2=0\frac{\left(\cot^{2}{\left(\frac{x + 1}{2} \right)} + 1\right) \cot{\left(\frac{x + 1}{2} \right)}}{2} = 0
Solve this equation
The roots of this equation
x1=1+πx_{1} = -1 + \pi

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
(,1+π]\left(-\infty, -1 + \pi\right]
Convex at the intervals
[1+π,)\left[-1 + \pi, \infty\right)
Horizontal asymptotes
Let’s find horizontal asymptotes with help of the limits of this function at x->+oo and x->-oo
limxcot(x+12)=cot()\lim_{x \to -\infty} \cot{\left(\frac{x + 1}{2} \right)} = - \cot{\left(\infty \right)}
Let's take the limit
so,
equation of the horizontal asymptote on the left:
y=cot()y = - \cot{\left(\infty \right)}
limxcot(x+12)=cot()\lim_{x \to \infty} \cot{\left(\frac{x + 1}{2} \right)} = \cot{\left(\infty \right)}
Let's take the limit
so,
equation of the horizontal asymptote on the right:
y=cot()y = \cot{\left(\infty \right)}
Inclined asymptotes
Inclined asymptote can be found by calculating the limit of cot((x + 1)/2), divided by x at x->+oo and x ->-oo
True

Let's take the limit
so,
inclined asymptote equation on the left:
y=xlimx(cot(x+12)x)y = x \lim_{x \to -\infty}\left(\frac{\cot{\left(\frac{x + 1}{2} \right)}}{x}\right)
True

Let's take the limit
so,
inclined asymptote equation on the right:
y=xlimx(cot(x+12)x)y = x \lim_{x \to \infty}\left(\frac{\cot{\left(\frac{x + 1}{2} \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:
cot(x+12)=cot(x212)\cot{\left(\frac{x + 1}{2} \right)} = - \cot{\left(\frac{x}{2} - \frac{1}{2} \right)}
- No
cot(x+12)=cot(x212)\cot{\left(\frac{x + 1}{2} \right)} = \cot{\left(\frac{x}{2} - \frac{1}{2} \right)}
- No
so, the function
not is
neither even, nor odd