0
Problem: find three solutions to z^3=-1.
DeMoivre's theorem is that (cos b + i sin b)^n = cos bn + i sin bn
So we can set
z= (cos b + i sin b),
n = 3
cos bn + i sin bn = -1.
From the last equation, we know that cos bn = -1, and sin bn = 0.
Three possible solutions are bn=pi, bn=3pi, bn=5pi. This gives three possible values of b:
b=pi/3
b=pi
b = 5pi/3.
Now using z= (cos b + i sin b), we can get three possible cube roots of -1:
z= (cos pi/3 + i sin pi/3),
z= (cos pi + i sin pi),
z= (cos 5pi/3 + i sin 5pi/3).
Working these out gives
-1/2+i*sqrt(3)/2
-1
-1/2-i*sqrt(3)/2
Add your answer:
Earn +20 pts
Why are the absolute values of a complex number and its conjugate always equal?
If you understand what the absolute value of a complex number is, skip to the tl;dr part at the bottom. The absolute value can be thought of as a sorts of 'norm', because it assigns a positive value to a number, which represents that number's "distance" from zero (except for the number zero, which has an absolute value of zero). For real numbers, the "distance" from zero is merely the number without it's sign. For complex numbers, the "distance" from zero is the length of the line drawn from 0 to the number plotted on the complex plane. In order to see why, take any complex number of the form a + b*i, where 'a' and 'b' are real numbers and 'i' is the imaginary unit. In order to plot this number on a complex plane, just simply draw a normal graph. The number is located at (a,b). In order to determine the distance from 0 (0,0) to our number (a,b) we draw a triangle using these three points: (0,0) (a,0) (a,b) Where the points (0,0) and (a,b) form the hypotenuse. The length of the hypotenuse is also the "distance" of a + b*i from zero. Because the legs run parallel to the x and y axes, the lengths of the two legs are 'a' and 'b'. By using the Pythagorean theorem, we can find the length of the hypotenuse as (a2 + b2)(1/2). Because the length of the hypotenuse is also the 'distance' of the complex number from zero on the complex plane, we have the definition: |a + b*i| = (a2 + b2)(1/2) ALRIGHT, almost there. tl;dr: Remember that the complex conjugate of a complex number a + b*i is a + (-b)*i. By plugging this into the Pythagorean theorem, we have: b2 = (-b)2 So: (a2 + (-b)2)(1/2) = (a2 + b2)(1/2) QED.
Can the answer to a quadratic equation be a decimal?
Yes. You can calculate the two roots of a quadratic equation by using the quadratic formula, and because there are square roots on the quadratic formula, and if the radicand is not a perfect square, so the answer to that equation has decimal.
When you ask the database more complex questions using comparison operators you are conducting a?
You are conducting a query.
How do you factor 4x squared plus 4x -1?
Given 4x2+4x-1 Using the formula for the roots of quadratic equation, (-b +/-./b2-4ac)/2a the roots for the above will be (-4+/-4./2)/8 = (-1+/-./2)/2 Hence the two roots are (-1+./2)/2 and (-1-./2)/2 As the roots are irrational, there is no possibility of getting factors.
How do you find the roots of a polynomial of graphed points?
Join the points using a smooth curve. If you have n points choose a polynomial of degree at most (n-1). You will always be able to find polynomials of degree n or higher that will fit but disregard them. The roots are the points at which the graph intersects the x-axis.
How do you find roots of z5 using demorves theorem?
z5 is an expression, not an equation and so cannot have roots.
How do you calculate equivalent resistance in complex circuits mathematically?
Using superposition theorem.
What is the use of thevenin's theorem?
By using Thevenin's theorem we can make a complex circuit into a simple circuit with a voltage source(Vth) in series with a resistance(Rth)
What the square roots of -256?
There are no real square roots of -256. But using complex numbers the square roots of -256 are 16i and -16i.
At most how many unique roots will a fifth-degree polynomial have?
5, Using complex numbers you will always get 5 roots.
Do every polynomial function has at least one complex zero?
No. Complex zeros always come in conjugate pairs. So if a+bi is one zero, then a-bi is also a zero.The fundamental theorem of algebra says"Every polynomial equation of degree n with complex coefficients has n roots in the complex numbers."If you want to know how many complex root a given polynomial has, you might consider finding out how many real roots it has. This can be done with Descartes Rules of signsThe maximum number of positive real roots can be found by counting the number of sign changes in f(x). The actual number of positive real roots may be the maximum, or the maximum decreased by a multiple of two.The maximum number of negative real roots can be found by counting the number of sign changes in f(-x). The actual number of negative real roots may be the maximum, or the maximum decreased by a multiple of two.Complex roots always come in pairs. That's why the number of positive or number of negative roots must decrease by two. Using the two rules for positive and negative signs along with the fact that complex roots come in pairs, you can determine the number of complex roots.
Can a theorem be proven using a corollary?
No, a corollary follows from a theorem that has been proven. Of course, a theorem can be proven using a corollary to a previous theorem.
What statement to a theorem can be proven easily using the theorem?
A corollary.
How do you find complex zeros of a polynomial of x3-1?
4
A corollary is a statement that can easily be proved using a theorem?
A corollary is a statement that can easily be proved using a theorem.
A corollary is a statement that can be easily proved using a theorem?
No. A corollary is a statement that can be easily proved using a theorem.
Is a theorem a statement that can be easily proved using a corollary?
No. A corollary is a statement that can be easily proved using a theorem.
