Answer:
Step-by-step explanation:
roots of a complex number is given by DeMoivre's formula.
![\sf \boxed{\bf r^{\frac{1}{n}}\left[Cos \dfrac{\theta + 2\pi k}{n}+i \ Sin \ \dfrac{\theta+2\pi k}{n}\right]}](https://tex.z-dn.net/?f=%5Csf%20%5Cboxed%7B%5Cbf%20r%5E%7B%5Cfrac%7B1%7D%7Bn%7D%7D%5Cleft%5BCos%20%5Cdfrac%7B%5Ctheta%20%2B%202%5Cpi%20k%7D%7Bn%7D%2Bi%20%5C%20Sin%20%5C%20%5Cdfrac%7B%5Ctheta%2B2%5Cpi%20k%7D%7Bn%7D%5Cright%5D%7D)
Here, k lies between 0 and (n -1) ; n is the exponent.
![\sf -1 + i\sqrt{3}](https://tex.z-dn.net/?f=%5Csf%20-1%20%2B%20i%5Csqrt%7B3%7D)
a = -1 and b = √3
![\sf \boxed{r=\sqrt{a^2+b^2}} \ and \ \boxed{\theta = Tan^{-1} \ \dfrac{b}{a}}](https://tex.z-dn.net/?f=%5Csf%20%5Cboxed%7Br%3D%5Csqrt%7Ba%5E2%2Bb%5E2%7D%7D%20%5C%20and%20%5C%20%5Cboxed%7B%5Ctheta%20%3D%20Tan%5E%7B-1%7D%20%5C%20%5Cdfrac%7Bb%7D%7Ba%7D%7D)
![\sf r = \sqrt{(-1)^2 + 3^2}\\\\ = \sqrt{1+9}\\\\=\sqrt{10}](https://tex.z-dn.net/?f=%5Csf%20r%20%3D%20%5Csqrt%7B%28-1%29%5E2%20%2B%203%5E2%7D%5C%5C%5C%5C%20%3D%20%5Csqrt%7B1%2B9%7D%5C%5C%5C%5C%3D%5Csqrt%7B10%7D)
![\sf \theta = tan^{-1} \ \dfrac{\sqrt{3}}{-1}\\\\ = tan^{-1} \ (-\sqrt{3})](https://tex.z-dn.net/?f=%5Csf%20%5Ctheta%20%3D%20tan%5E%7B-1%7D%20%5C%20%5Cdfrac%7B%5Csqrt%7B3%7D%7D%7B-1%7D%5C%5C%5C%5C%20%3D%20tan%5E%7B-1%7D%20%5C%20%28-%5Csqrt%7B3%7D%29)
![\sf = \dfrac{-\pi }{3}](https://tex.z-dn.net/?f=%5Csf%20%3D%20%5Cdfrac%7B-%5Cpi%20%7D%7B3%7D)
n = 4
For k = 0,
![\sf z = \sqrt[4]{10}\left[Cos \ \dfrac{\dfrac{-\pi}{3} +0}{4}+iSin \ \dfrac{\dfrac{-\pi}{3}+0}{4}\right] \\\\\\z= \sqrt[4]{10} \left[Cos \ \dfrac{ -\pi }{12}+iSin \ \dfrac{-\pi}{12}\right]\\\\\\z = \sqrt[4]{10}\left[-Cos \ \dfrac{\pi}{12}-i \ Sin \ \dfrac{\pi}{12}\right]](https://tex.z-dn.net/?f=%5Csf%20z%20%3D%20%5Csqrt%5B4%5D%7B10%7D%5Cleft%5BCos%20%5C%20%5Cdfrac%7B%5Cdfrac%7B-%5Cpi%7D%7B3%7D%20%2B0%7D%7B4%7D%2BiSin%20%20%5C%20%5Cdfrac%7B%5Cdfrac%7B-%5Cpi%7D%7B3%7D%2B0%7D%7B4%7D%5Cright%5D%20%5C%5C%5C%5C%5C%5Cz%3D%20%5Csqrt%5B4%5D%7B10%7D%20%5Cleft%5BCos%20%5C%20%5Cdfrac%7B%20-%5Cpi%20%20%7D%7B12%7D%2BiSin%20%20%5C%20%5Cdfrac%7B-%5Cpi%7D%7B12%7D%5Cright%5D%5C%5C%5C%5C%5C%5Cz%20%3D%20%5Csqrt%5B4%5D%7B10%7D%5Cleft%5B-Cos%20%5C%20%5Cdfrac%7B%5Cpi%7D%7B12%7D-i%20%5C%20Sin%20%5C%20%5Cdfrac%7B%5Cpi%7D%7B12%7D%5Cright%5D)
For k =1,
![\sf z = \sqrt[4]{10}\left[Cos \ \dfrac{5\pi}{12}+i \ Sin \ \dfrac{5\pi}{12}\right]](https://tex.z-dn.net/?f=%5Csf%20z%20%3D%20%5Csqrt%5B4%5D%7B10%7D%5Cleft%5BCos%20%5C%20%5Cdfrac%7B5%5Cpi%7D%7B12%7D%2Bi%20%5C%20Sin%20%5C%20%5Cdfrac%7B5%5Cpi%7D%7B12%7D%5Cright%5D)
For k =2,
![z = \sqrt[4]{10}\left[Cos \ \dfrac{11\pi}{12}+i \ Sin \ \dfrac{11\pi}{12}\right]](https://tex.z-dn.net/?f=z%20%3D%20%5Csqrt%5B4%5D%7B10%7D%5Cleft%5BCos%20%5C%20%5Cdfrac%7B11%5Cpi%7D%7B12%7D%2Bi%20%5C%20Sin%20%5C%20%5Cdfrac%7B11%5Cpi%7D%7B12%7D%5Cright%5D)
For k = 3,
![\sf z = \sqrt[4]{10}\left[Cos \ \dfrac{17\pi}{12}+i \ Sin \ \dfrac{17\pi}{12}\right]](https://tex.z-dn.net/?f=%5Csf%20z%20%3D%20%5Csqrt%5B4%5D%7B10%7D%5Cleft%5BCos%20%5C%20%5Cdfrac%7B17%5Cpi%7D%7B12%7D%2Bi%20%5C%20Sin%20%5C%20%5Cdfrac%7B17%5Cpi%7D%7B12%7D%5Cright%5D)
For k = 4,
![\sf z =\sqrt[4]{10}\left[Cos \ \dfrac{23\pi}{12}+i \ Sin \ \dfrac{23\pi}{12}\right]](https://tex.z-dn.net/?f=%5Csf%20z%20%3D%5Csqrt%5B4%5D%7B10%7D%5Cleft%5BCos%20%5C%20%5Cdfrac%7B23%5Cpi%7D%7B12%7D%2Bi%20%5C%20Sin%20%5C%20%5Cdfrac%7B23%5Cpi%7D%7B12%7D%5Cright%5D)
Answer:
Radius of the convergence is R = ![\frac{1}{21}](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B21%7D)
and,
The Interval of convergence is ![-\frac{1}{21}](https://tex.z-dn.net/?f=-%5Cfrac%7B1%7D%7B21%7D%3Cx%3C%5Cfrac%7B1%7D%7B21%7D)
Step-by-step explanation:
Given function : Σ(21x)^k
Now,
Using the ratio test, we have
R = ![\lim_{n \to \infty} |\frac{21x^{k+1}}{21x^{k}}|](https://tex.z-dn.net/?f=%5Clim_%7Bn%20%5Cto%20%5Cinfty%7D%20%7C%5Cfrac%7B21x%5E%7Bk%2B1%7D%7D%7B21x%5E%7Bk%7D%7D%7C)
or
R = ![\lim_{n \to \infty} |\frac{21x^{k}\times21x^{1}}{21x^{k}}|](https://tex.z-dn.net/?f=%5Clim_%7Bn%20%5Cto%20%5Cinfty%7D%20%7C%5Cfrac%7B21x%5E%7Bk%7D%5Ctimes21x%5E%7B1%7D%7D%7B21x%5E%7Bk%7D%7D%7C)
or
R = ![\lim_{n \to \infty} |21x^{1}|](https://tex.z-dn.net/?f=%5Clim_%7Bn%20%5Cto%20%5Cinfty%7D%20%7C21x%5E%7B1%7D%7C)
now,
for convergence R|x| < 1
Therefore,
< 1
or
![-\frac{1}{21}](https://tex.z-dn.net/?f=-%5Cfrac%7B1%7D%7B21%7D%3Cx%3C%5Cfrac%7B1%7D%7B21%7D)
and,
Radius of the convergence is R = ![\frac{1}{21}](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B21%7D)
and,
The Interval of convergence is ![-\frac{1}{21}](https://tex.z-dn.net/?f=-%5Cfrac%7B1%7D%7B21%7D%3Cx%3C%5Cfrac%7B1%7D%7B21%7D)
Answer:
yes
Step-by-step explanation:
it is reflected across the y axis
Answer:
All of the values in the data are used in calculating the mean.
The sum of the deviations is zero.
There is only one mean for a set of data.
Step-by-step explanation:
Required
True statement about arithmetic mean
(a) False
The mean can be equal to, greater than or less than the median
(b) True
The arithmetic mean is the summation of all data divided by the number of data; hence, all values are included.
(c) True
All mean literally represent the distance of each value from the average; so, when each value used in calculating the mean is subtracted from the calculated mean, then the end result is 0. i.e.![\sum(x - \bar x) = 0](https://tex.z-dn.net/?f=%5Csum%28x%20-%20%5Cbar%20x%29%20%3D%200)
(d) True
The mean value of a distribution is always 1 value. When more values are added to the existing values or some values are removed from the existing values, the mean value will change.
(e) False
Nominal data are not numerical or quantitative data; hence, the mean cannot be calculated.
Answer:
A
Step-by-step explanation: