Calculus - Complex numbers (5) Flashcards

(32 cards)

1
Q

Polar form into rectangular form - the power of something (^5)

A

To the r, do ^5.
To the arg, times by 5.

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2
Q

If something lies on the line y=x and need to find i & r

A

Make the real parts = the imaginary parts. Seperate them and make them equal.

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3
Q

If it says “it won’t be…” or “doesn’t lie on the line…”

A

Then make it equal what it’s not equal to and show that there are no possible answers.

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4
Q

if w is the subject and it’s not by itself

A

Rearrange it so that w is by itself, then sub that into other equations.

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5
Q

If z has multiple numbers, and one is 2 + 3i

A

One of the others must be 2-3i

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6
Q

De moviers theorum if it’s z^4. Find out all 4 answers

A

Change into polar form! (pi, 2pi, etc)
Find the 4th root of the first number
Minus the power of k, or other by 4
divide the arg by 4, and add 2pi/? each time

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7
Q

If asked to give an answer in terms of p

A

make sure there are no xs in there! do anything, substitute p in for some xs

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8
Q

If real + imaginary = 0

A

Real = 0
Imaginary =0

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9
Q

If it says y=mx+?

A

Can sub that in for y

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10
Q

Finding the tangent of something

A

Discriminant = 0

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11
Q

If a question has a root symbol and you wanna do the quadratic/discriminant

A

get rid of the root by squaring. Do the full brackets

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12
Q

Something divisible by two numbers, and they both have the same remainder

A

Put x into those equations and make them equal

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13
Q

What is the argument?

A

The angle. Always in radians

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14
Q

Finding out that real = imaginary

A

Get rid of the i, make the thing equal 0

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15
Q

If it says “find k” instead of find value/s of k

A

K prob has one answer. check it

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16
Q

When arg = pi/4 when dealing with real = imaginary

A

tan(pi/4) = 1. Use this to bring the fraction up

17
Q

Equation where there are multiple xs

A

Rearrange so that there is only 1 x, don’t necessarily square both sides when there is a root sign.

18
Q

When finding the discriminant, you find another quadratic

A

Complete the square
Or put in the calc to see what that variable =

19
Q

Z = x+iy, real = imaginary

A

Can be written as x+xy

20
Q

Modulus of a fraction

A

Rationalize the denominator then get rid of the modulus

21
Q

How to turn rect into polar form

A

Options - complex - arg

22
Q

Tangent only intersecting at one point

A

Discriminant = 0. Y=mx+c, put that in.

23
Q

If it is 1 + a fraction

A

multiply by 1+x+iy / 1+x+iy

24
Q

Z to the 3 + A has … as a solution. Find A & Other 2 solutions

A

Z=… into the calc to find A.
Z-(Z1) x (Z-(z2) x (pz+q) = Answer
Z x Z x Pz = Z to the 3
Stuff in the brackets equal to A, rearrange for q.
Rearrange the 3rd bracket to find what 1z =.

25
When wanting to find z and it's in a quadratic
Treat it as an x, put into calc/solve it the hard way
26
X+iy in a fraction, real = something, imaginary = something.
Keep the imaginary with the divided parts even if they're real.
27
In an E question, there is x squareds & xs, need to form a circle equation
Put the xs together in a bracket and square it, half the number of the x (perfect square). Make it equal to whatever is left over?
28
If asked to represent z
Do 2 fractions, 1 real & 1 i. Make sure they have the same denominator. It's like a + bi
29
If something has equal roots
Discriminant = 0
30
If w is in a fraction and equals something
DON'T SAY THAT W=X+IY, as it doesn't even say that w is a complex #! Just times the answer by the denominator
31
In a modulus, there is a number before the 2 vertical lines
Square everything like normal, and make sure to times that number by all the brackets
32
How to find arg(u/v)
Can do the fraction thing and simplyify But, arg(u/v) = arg(u) - arg(v)