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Complex Numbers

The square root of negative one, which we now call the imaginary unit, was once thought to be an absurd notion. However, through the diligent studies of open-minded mathematicians, it was shown that the real numbers were actually just one part of a larger set of numbers known as the complex numbers, the other part being the imaginary numbers. Please direct all questions about these surprisingly useful and applicable numbers into this category.

887 Questions

How do change a complex number to its standard form?

It isn't clear in what form you have the complex number. But you can change it from the form (absolute value, angle) to the form (real part + imaginary part) using the polar-rectangular conversion available on scientific calculators (and the other way round, with the rectangular-polar conversion). Note that a complex number in the form (real part + imaginary part) is most appropriate for addition and subtraction, while a complex number of the form (absolute value, angle) is most appropriate for multiplication or division, so depending on the operations, you may want to convert back and forth several times.

What is the exponential form of complex numbers?

Complex numbers can be represented as reiƟ, where r is the distance from the origin, and Ɵ is the angle (in radians) with the positive real-axis (horizontal axis).

What are the roots of complex numbers in mathematics?

See the answer to the related question: 'How do you solve the power of an imaginary number?' (Link below)

What is the largest number of pieces you could cut a pie into with 4 straight cuts of a knife?

This depends on whether the pie is thick or not - if you mean 4 cuts from the top downwards, then you can get nine, if you cut it right. Imagine a clock face. cut 1 - from 1:00 to 5:00 cut 2 - from 11:00 to 7:00 cut 3 - from 10:00 to 2:00 cut 4 - from 8:00 to 4:00 Alternatively, with a thick pie you could make three top-downwards cuts to give six people and one through the middle of the pie, parallel to the plate, to divide each of those pieces in two - giving a total of 12 pieces. (This works when if you're dealing with 'cake' instead of 'pie'.)

Is the sum of two pure imaginary numbers always a pure imaginary number?

Yes, the only argument would be the example, i + (-i) = 0. However, many people don't realize that 0 is both a purely real and pure imaginary number since it lies on both axes of the complex plane.

How do you determine the absolute value of a complex conjugate?

the absolute value of x + iy is equal to (x^2+y^2)^.5

and is the same for the conjugate, x-iy

Examples of complex numbers?

5+6i , -2-2i , 100+i.

A complex number consists of a real part and an imaginary part: a+bi where 'i' is the imaginary unit (sq.rt(-1)).

What is complex number system?

All pairs of numbers, written in the form a + bi (for example: 3 + 5i, or 7 - 2i, etc.), where the first number is called (for historical reasons) the "real part" and the second number the "imaginary part". Complex numbers can be graphed as points on a plane. They have important applications in several fields of science, arts, and pure mathematics.

What is the name for the number 1000000000000000000000?

Yes -- one sextillion.

Also according to one scientific hypothesis, this is the estimated number for the number of stars within our current universe with the number slowly increasing as time progresses.

What are the complex number system?

The set of complex numbers consists of real numbers and imaginary numbers (multiples of the square root of -1), and then a combination of the two sets of numbers. Complex numbers are often depicted graphically, with real numbers on the horizontal axis, and imaginary numbers on the vertical axis. See related link for more information.

What is complex math?

Complex math covers how to do operations on complex numbers. Complex numbers include real numbers, imaginary numbers, and the combination of real+imaginary numbers.

How do you solve the power of an imaginary number?

It helps to think about imaginary and complex numbers graphically.

Euler's Formula (see related link): eiΘ = cos(Θ) + i sin(Θ) {Θ is in radians}. Note that both eiΘ and [cos(Θ) + i sin(Θ)] have a magnitude of 1, so multiply by the magnitude: AeiΘ = Acos(Θ) + Ai sin(Θ). You now have a graphical representation of complex numbers, with real numbers on the horizontal axis, pure imaginaries on the vertical axis, and all other complex numbers placed on the 'complex plane'. The angle is a direction, from the origin, and the magnitude A tells how far away from the origin that the position is.

With pure imaginary numbers you can have Θ = pi/2 radians (90°, vertical), and let A be either positive or negative (up or down). From the rules for exponents and powers, you now have the imaginary number z = ei*pi/2, and (ex)n = ex*n, so zn = (ei*pi/2)n = ei*n*pi/2 , so switching to degrees for simplicity:

n Θ

0 0° (Points to the right: positive real)

1 90° (Pointing straight up: imaginary positive number)

2 180° (Points to the left: real negative number)

3 270° (Points straight down: imaginary negative)

4 360° (Points to the right: real positive ), same as 0°

Note it goes in a circle and repeats. Odd integer values of n will be pure imaginary and even integers will be real numbers. Non-integers will put the angle so it is a complex number. Negative exponents cause it to move in a clockwise direction on the circle, rather than counterclockwise (for positive exponents).

Now that you know the direction, you only need to take An, as a power, and then point it in the proper direction. So if the power of A yields a positive number, the answer will be in the direction, but if it yields a negative number (odd integer powers of a negative A), then it's in the opposite direction (add 180° to the angle).

What is birdman real number?

i think birdman is rich than 5o cent and that is a fact i think birdman is rich than 5o cent and that is a fact

Are imaginary numbers used in real life?

Yes they are. They can be used to depict fields around high voltage wires.

See the below related link for the field (z-1)/(z+1).

How do you figure out complex number problems?

It depends on what you're trying to do with the complex numbers, and what level of math understanding that you are at. Some tips:

Treat the i like a variable (like x): example: Add a + bx & c + dx = a + bx + c + dx = a + c + bx + dx = (a + c) + (b + d)x. Now, substitute x = i

Multiplying: (a + bx) * (c + dx) = ac + adx + bcx + bdx2 = ac + (ad + bc)x + bdx2, when substituting x = i in this one: ac + (ad + bc)i + bdi2, but i2 = -1, so we have:

ac + (ad + bc)i - bd = (ac - bd) + (ad + bc)i

If you are familiar with vectors, you can treat complex numbers as vectors in the complex plane, and do some operations on them that way. See related link.

How are imaginary numbers used?

In this case, they can help visualize the electromagnetic field around wires

carrying current by the formula (z-1)/(z+1)

Refer to the related link.

How do you simplify complex numbers to a negative exponent?

Lets try z^-1 which is 1/z. Now z=x+iy then 1/z = 1/(x+iy). This is equal to

(x-iy)/((x+iy)(x-iy)) and is equal to (x-iy)/(xx+yy). The real part is u=x/(xx+yy) and the imaginary part is -y/(xx+yy). Don't forget that i squared is -1 when working out (x+iy)(x-iy). Get a good program like Mathmatica as higher exponents get real time consuming and will cause brain damage!

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How do you convret polar form of complex number into algebraic form?

For a complex number in polar form with Magnitude, and Angle:

(Magnitude)*(cos(angle) + i*sin(angle)) will give the form: a + bi

What is an imaginary number and how is it expressed?

An imaginary number is a number that cannot exist. An example of an imaginary number would be: the square root of negative nine, or any negative number.

When I try to think of any two of the same numbers that would multiply together to be negative nine, all I can think of is 3 or -3. when I square both of those numbers, I get the number 9, not -9. When I multiply two negatives together, I get a positive number, therefore there is no possible way to get the square root of -9, or any negative number.

When did Argand graph imaginary numbers?

The idea of graphing complex numbers was published by Argand in 1806. See related link.

What is the exponential form for complex numbers?

Exponential form is similar to 'polar form'. Call the Magnitude A, and the angle θ .

Then the number is represented as A*eiθ (θ in radians). To convert to rectangular form, use Euler's formula:

  • eiθ = cos(θ) + i*sin(θ)

So the complex number A*eiθ = A*cos(θ) + A*i*sin(θ)

What are two complex numbers whose product is 10?

The set of complex numbers includes the set of real numbers. The real number system is just with the imaginary part set to 0.

example: z = 5 + i0 = 5

So the simple answer would be (2+i0)*(5+i0) = 10, so the complex values (2,0) and (5,0) get the result your looking for.

If you want a pair not on the real line then 2*exp(i*pi/4) and 5*exp(-i*pi/4) will do.

If you multiply the two complex numbers you get 2*5*exp(i*(pi/4-pi/4)) which is just 10.

Since pure imaginary numbers are also part of the set of complex numbers, you could have -2i * 5i, the i's multiplied together yield -1 and multiplied by -10 = 10.

Evaluate and express this complex number in standard form the absulote value of 5-12i?

The absolute value of a complex number is it's magnitude (distance from the origin). Think about complex numbers graphically, with reals on the horizontal axis, and imaginaries on the vertical axis. Now you have a right triangle: From the origin move to the right 5 units, then move down 12 units. The absolute value, or magnitude, is the length of the hypotenuse.

For this triangle, it is 13: sqrt(5^2 + 12^2) = sqrt(25+144) = sqrt(169) = 13. For magnitudes, we are only interested in the positive square root.