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1.2 Complex Numbers

Total questions: 20

Worksheet time: 13mins

Name
Class
Date
1.

Which of the following is a complex number?

a)

2121

b)

a+ba+b

c)

2+2i2+2i

d)

x+yx+y

2.

What is the Cartesian form of a complex number?

a)

z=1a+biz=\frac{1}{a+bi}

b)

z=1r(cosθ+isinθ)z=\frac{1}{r\left(\cos\theta+i\sin\theta\right)}

c)

z=a+biz=a+bi

d)

z=r(cosθ+isinθ)z=r\left(\cos\theta+i\sin\theta\right)

3.

Complex number consist of ...

a)

Spare part

b)

Imaginary part

c)

Real part

d)

Illusionary part

4.

What is
 i2=i^2=  


a)

 1-1  

b)

 11  

c)

 1\sqrt{-1}  

d)

 1-\sqrt{1}  

5.

 9=\sqrt{-9}=  

a)

 33  

b)

 3-3  

c)

 3i3i  

d)

 3i-3i  

6.

Find the sum (32157i)+(3+37i)\left(\frac{\sqrt{3}}{2}-\frac{15}{7}i\right)+\left(\sqrt{3}+\frac{3}{7}i\right)  

a)

 332187i\frac{3\sqrt{3}}{2}-\frac{18}{7}i  

b)

 3+187i\sqrt{3}+\frac{18}{7}i  

c)

 3+127i\sqrt{3}+\frac{12}{7}i  

d)

 332127i\frac{3\sqrt{3}}{2}-\frac{12}{7}i  

7.

Simplify 3i(4+2i)-3i\left(4+2i\right)  


a)

 12i6i2-12i-6i^2  

b)

 12i6-12i-6  

c)

 12i+6i2-12i+6i^2  

d)

 612i6-12i  

8.

How to change z=123iz=\frac{1}{2-3i}  to  z=a+biz=a+bi  ?

a)

Bring the denominator to the other side

b)

Change the sign of the imaginary part at the denominator

c)

Rationalise by multiplying with conjugate

9.

Given a complex number 2+3i2+3i  . What is its conjugate?

a)

 23i-2-3i  

b)

 23i2-3i  

c)

 2+3i-2+3i  

d)

 2+3i2+3i  

10.

Given that z=123iz=\frac{1}{2-3i}  can be written as  z=a+biz=a+bi . Find  aa  and  bb  . 


a)

 a=213, b=313a=\frac{2}{13},\ b=\frac{3}{13}  

b)

 a=2, b=3a=2,\ b=3  

c)

 a=25, b=35a=-\frac{2}{5},\ b=-\frac{3}{5}  

d)

 a=2, b=3a=-2,\ b=-3  

11.

Where is point C located?

a)

2 + i

b)

-3

c)

2i

d)

-1 - i

12.

Where is 1i-1-i  located at ?

a)

A

b)

B

c)

C

d)

D

13.

What is the modulus for a complex number?

a)

r=a2b2r=\sqrt{a^2-b^2}

b)

r=a2(bi)2r=\sqrt{a^2-\left(bi\right)^2}

c)

r=a2+b2r=\sqrt{a^2+b^2}

d)

r=a2+(bi)2r=\sqrt{a^2+\left(bi\right)^2}

14.

Find the modulus for z=1iz=-1-i  


a)

 2\sqrt{2}  

b)

 00  

c)

 22  

d)

 11  

15.

What is the argument of zz  ?


a)

 θ=α\theta=-\alpha  in the 4th quadrant

b)

 θ=(πα)\theta=-\left(\pi-\alpha\right)  in the 3rd quadrant

c)

 θ=πα\theta=\pi-\alpha  in the 2nd quadrant

d)

 θ=α\theta=\alpha  in the 1st quadrant

16.

Find α\alpha  for
  z=1iz=-1-i  

a)

 0.7854-0.7854  

b)

 0.8-0.8 

c)

 0.78540.7854  

d)

 0.80.8  

17.

Find the argument, θ \theta\   for  z=1iz=-1-i  

a)

 2.3562-2.3562  

b)

 2.35622.3562  

c)

 0.78540.7854  

d)

 0.7854-0.7854  

18.

What is the polar form of a complex number?

a)

z=1a+biz=\frac{1}{a+bi}

b)

z=1r(cosθ+isinθ)z=\frac{1}{r\left(\cos\theta+i\sin\theta\right)}

c)

z=a+biz=a+bi

d)

z=r(cosθ+isinθ)z=r\left(\cos\theta+i\sin\theta\right)

19.

Write z=1iz=-1-i  in polar form

a)

 2(sin0.7854+icos0.7854)\sqrt{2}\left(\sin0.7854+i\cos0.7854\right)  

b)

 2(sin(2.3562)+icos(2.3562))\sqrt{2}\left(\sin\left(-2.3562\right)+i\cos\left(-2.3562\right)\right)  

c)

 2(cos0.7854+isin0.7854)\sqrt{2}\left(\cos0.7854+i\sin0.7854\right)  

d)

 2(cos(2.3562)+isin(2.3562))\sqrt{2}\left(\cos\left(-2.3562\right)+i\sin\left(-2.3562\right)\right)   

20.

Overall, rate your understanding on 1.2 Complex Numbers

a)

Okay jak miss

b)

Saya masih confuse sikit2

c)

Saya tak faham apa2 langsung miss