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Higher Level Mathematics

Ibrahim Wazir, Tim Garry, Peter Ashbourne

Chapter 10

Complex Numbers - all with Video Answers

Educators


Section 1

Complex numbers, sums, products and quotients

03:13

Problem 1

Express each of the following numbers in the form $a+b i$.
$$5+\sqrt{-4}$$

Asif Khan
Asif Khan
Numerade Educator
03:12

Problem 2

Express each of the following numbers in the form $a+b i$.
$$7-\sqrt{-7}$$

Asif Khan
Asif Khan
Numerade Educator
01:58

Problem 3

Express each of the following numbers in the form $a+b i$.
$$-6$$

Asif Khan
Asif Khan
Numerade Educator
02:17

Problem 4

Express each of the following numbers in the form $a+b i$.
$$-\sqrt{49}$$

Asif Khan
Asif Khan
Numerade Educator
03:29

Problem 5

Express each of the following numbers in the form $a+b i$.
$$\sqrt{-81}$$

Asif Khan
Asif Khan
Numerade Educator
05:28

Problem 6

Express each of the following numbers in the form $a+b i$.
$$-\sqrt{\frac{-25}{16}}$$

Asif Khan
Asif Khan
Numerade Educator
02:03

Problem 7

Perform the following operations and express your answer in the form $a+b i$.
$$(-3+4 i)+(2-5 i)$$

Asif Khan
Asif Khan
Numerade Educator
01:58

Problem 8

Perform the following operations and express your answer in the form $a+b i$.
$$(-3+4 i)-(2-5 i)$$

Asif Khan
Asif Khan
Numerade Educator
03:35

Problem 9

Perform the following operations and express your answer in the form $a+b i$.
$$(-3+4 i)(2-5 i)$$

Asif Khan
Asif Khan
Numerade Educator
02:00

Problem 10

Perform the following operations and express your answer in the form $a+b i$.
$$3 i-(2-4 i)$$

Asif Khan
Asif Khan
Numerade Educator
04:24

Problem 11

Perform the following operations and express your answer in the form $a+b i$.
$$(2-7 i)(3+4 i)$$

Asif Khan
Asif Khan
Numerade Educator
04:17

Problem 12

Perform the following operations and express your answer in the form $a+b i$.
$$(1+i)(2-3 i)$$

Asif Khan
Asif Khan
Numerade Educator
06:57

Problem 13

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{3+2 i}{2+5 i}$$

Asif Khan
Asif Khan
Numerade Educator
06:56

Problem 14

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{2-i}{3+2 i}$$

Asif Khan
Asif Khan
Numerade Educator
03:57

Problem 15

Perform the following operations and express your answer in the form $a+b i$.
$$\left(\frac{2}{3}-\frac{1}{2} i\right)+\left(\frac{1}{3}+\frac{1}{2} i\right)$$

Asif Khan
Asif Khan
Numerade Educator
07:12

Problem 16

Perform the following operations and express your answer in the form $a+b i$.
$$\left(\frac{2}{3}-\frac{1}{2} i\right)\left(\frac{2}{3}+\frac{1}{2} i\right)$$

Asif Khan
Asif Khan
Numerade Educator
09:36

Problem 17

Perform the following operations and express your answer in the form $a+b i$.
$$\left(\frac{2}{3}-\frac{1}{2} i\right) \div\left(\frac{1}{3}+\frac{1}{2} i\right)$$

Asif Khan
Asif Khan
Numerade Educator
03:52

Problem 18

Perform the following operations and express your answer in the form $a+b i$.
$$(2+i)(3-2 i)$$

Asif Khan
Asif Khan
Numerade Educator
07:04

Problem 19

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{1}{i}(3-7 i)$$

Asif Khan
Asif Khan
Numerade Educator
02:29

Problem 20

Perform the following operations and express your answer in the form $a+b i$.
$$(2+5 i)-(-2-5 i)$$

Asif Khan
Asif Khan
Numerade Educator
06:22

Problem 21

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{13}{5-12 i}$$

Asif Khan
Asif Khan
Numerade Educator
08:45

Problem 22

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{12 i}{3+4 i}$$

Asif Khan
Asif Khan
Numerade Educator
04:38

Problem 23

Perform the following operations and express your answer in the form $a+b i$.
$$3 i\left(3-\frac{2}{3} i\right)$$

Asif Khan
Asif Khan
Numerade Educator
04:23

Problem 24

Perform the following operations and express your answer in the form $a+b i$.
$$(3+5 i)(6-10 i)$$

Asif Khan
Asif Khan
Numerade Educator
08:36

Problem 25

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{39-52 i}{24+10 i}$$

Asif Khan
Asif Khan
Numerade Educator
06:30

Problem 26

Perform the following operations and express your answer in the form $a+b i$.
$$(7-4 i)^{-1}$$

Asif Khan
Asif Khan
Numerade Educator
06:17

Problem 27

Perform the following operations and express your answer in the form $a+b i$.
$$(5-12 i)^{-1}$$

Asif Khan
Asif Khan
Numerade Educator
11:48

Problem 28

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{3}{3-4 i}+\frac{2}{6+8 i}$$

Asif Khan
Asif Khan
Numerade Educator
02:27

Problem 28

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{3}{3-4 i}+\frac{2}{6+8 i}$$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
03:18

Problem 29

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{(7+8 i)(2-5 i)}{5-12 i}$$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
02:49

Problem 30

Perform the following operations and express your answer in the form $a+b i$.
$$\frac{5-\sqrt{-144}}{3+\sqrt{-16}}$$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
03:12

Problem 32

$(2+y i)(x+i)=1+3 i,$ where $x$ and $y$ are real numbers. Solve for $x$ and $y$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
04:07

Problem 33

a) Evaluate $(1+i \sqrt{3})^{3}$
b) Prove that $(1+i \sqrt{3})^{6 n}=8^{2 n},$ where $n \in Z^{+}$
c) Hence, find $(1+i \sqrt{3})^{48}$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
04:45

Problem 34

a) Evaluate $(-\sqrt{2}+i \sqrt{2})^{2}$
b) Prove that $(-\sqrt{2}+i \sqrt{2})^{4 k}=(-16)^{k},$ where $k \in Z^{+}$
c) Hence, find $(-\sqrt{2}+i \sqrt{2})^{46}$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
04:10

Problem 35

If $z$ is a complex number such that $|z+4 i|=2|z+i|,$ find the value of $|z|$ $(|z|=\sqrt{x^{2}+y^{2}} \text { where } z=x+i y .)$

Ahmet Yavas
Ahmet Yavas
Numerade Educator
02:40

Problem 36

Find the complex number $z$ and write it in the form $a+$ bi if $z=3+\frac{2 i}{2-i \sqrt{2}}$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
03:06

Problem 37

Find the values of the two real numbers $x$ and $y$ such that $(x+i y)(4-7 i)=3+2 i$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
02:27

Problem 38

Find the complex number $z$ and write it in the form $a+$ bi if $i(z+1)=3 z-2$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
02:50

Problem 39

Find the complex number $z$ and write it in the form $a+$ bi if $\frac{2-i}{1+2 i} \sqrt{z}=2-3 i$.

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
03:30

Problem 40

Find the values of the two real numbers $x$ and $y$ such that $(x+i y)^{2}=3-4 i$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
07:28

Problem 41

a) Find the values of the two real numbers $x$ and $y$ such that $(x+i y)^{2}=-8+6 i$
b) Hence, solve the following equation
$$z^{2}+(1-i) z+2-2 i=0$$

Ahmet Yavas
Ahmet Yavas
Numerade Educator
08:42

Problem 42

If $z \in \mathbb{C},$ find all solutions to the equation $z^{3}-27 i=0$.

Ahmad Reda
Ahmad Reda
Numerade Educator
04:59

Problem 43

Given that $z=\frac{1}{2}+2 i$ is a zero of the polynomial $f(x)=4 x^{3}-16 x^{2}+29 x-51$ find the other zeros.

Chris Trentman
Chris Trentman
Numerade Educator
03:35

Problem 44

Find a polynomial function with integer coefficients and lowest possible degree that has $\frac{1}{2},-1$ and $3+i \sqrt{2}$ as zeros.

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
02:42

Problem 45

Find a polynomial function with integer coefficients and lowest possible degree that has -2,-2 and $1+i \sqrt{3}$ as zeros.

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
02:19

Problem 46

Given that $z=5+2 i$ is a zero of the polynomial $f(x)=x^{3}-7 x^{2}-x+87,$ find the other zeros.

AG
Ankit Gupta
Numerade Educator
03:09

Problem 47

Given that $z=1-i \sqrt{3}$ is a zero of the polynomial $f(x)=3 x^{3}-4 x^{2}+8 x+8$ find the other zeros.

Chris Trentman
Chris Trentman
Numerade Educator
02:11

Problem 48

Let $z \in \mathbb{C} .$ If $\frac{z}{z^{*}}=a+b i,$ show that $|a+b i|=1$

Avinash Vishwakarma
Avinash Vishwakarma
Numerade Educator
01:49

Problem 49

Given that $z=(k+i)^{4}$ where $k$ is a real number, find all values of $k$ such that
a) $z$ is a real number
b) $z$ is purely imaginary.

Gaurav Kalra
Gaurav Kalra
Numerade Educator
01:31

Problem 50

Solve the system of equations.
$$\begin{array}{l}i z_{1}+2 z_{2}=3-i \\2 z_{1}+(2+i) z_{2}=7+2 i\end{array}$$

James Kiss
James Kiss
Numerade Educator
00:31

Problem 51

Solve the system of equations.
$i z_{1}-(1+i) z_{2}=3$
$(2+i) z_{1}+i z_{2}=4$

AG
Ankit Gupta
Numerade Educator