Complex Numbers in Mathematics
Learn about complex numbers, including rational and irrational numbers, algebraic and trigonometric forms, conjugates, addition, subtraction, multiplication, division, equality, and more. Practice problems included.
Complex Numbers in Mathematics
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Chapter 39 Complex Numbers By Chtan FYHS-Kulai
consist of all positive and negative integers, all rational numbers and irrational numbers. By Chtan FYHS-Kulai
Rational numbers are of the form p/q, where p, q are integers. Irrational numbers are By Chtan FYHS-Kulai
Complex number notation By Chtan FYHS-Kulai
Algebra form Trigonometric form Notation index form By Chtan FYHS-Kulai
Complex numbers are defined as numbers of the form : or By Chtan FYHS-Kulai
is represented by are real numbers. A complex number consists of 2 parts. Real part and imaginary part. By Chtan FYHS-Kulai
Notes: • When b=0, the complex number is Real • When a=0, the complex number is imaginary • The complex number is zero iff a=b=0 By Chtan FYHS-Kulai
VENN DIAGRAMRepresentation • All numbers belong to the Complex number field, C. The Real numbers, R, and the imaginary numbers, i, are subsets of C asillustrated below. Complex Numbers a + bi Real Numbers a + 0i Imaginary Numbers 0 + bi
Conjugate complex number By Chtan FYHS-Kulai
Conjugate complex numbers The complex numbers and are called conjugate numbers. By Chtan FYHS-Kulai
is conjugate of . By Chtan FYHS-Kulai
e.g. 1 Solve the quadratic equation Soln: By Chtan FYHS-Kulai
e.g. 2 Factorise . Soln: By Chtan FYHS-Kulai
Representation of complex number in an Argand diagram By Chtan FYHS-Kulai
(Im) y P(a,b) x (Re) 0 P’(-a,-b) Argand diagram By Chtan FYHS-Kulai
e.g. 3 If P, Q represent the complex numbers 2+i, 4-3i in the Argand diagram, what complex number is represented by the mid-point of PQ? By Chtan FYHS-Kulai
y (Im) Soln: P(2,1) x (Re) 0 Q(4,-3) Mid-point of PQ is (3,-1) is the complex number. By Chtan FYHS-Kulai
Do pg.272 Ex 20a By Chtan FYHS-Kulai
Equality of complex numbers By Chtan FYHS-Kulai
The complex numbers and are said to be equal if, and only if, a=c and b=d. By Chtan FYHS-Kulai
e.g. 4 Find the values of x and y if (x+2y)+i(x-y)=1+4i. Soln: x+2y=1; x-y=4 2y+y=1-4; 3y=-3, y=-1 x-(-1)=4, x=4-1=3 By Chtan FYHS-Kulai
Addition of complex numbers By Chtan FYHS-Kulai
If then By Chtan FYHS-Kulai
Subtraction of complex numbers By Chtan FYHS-Kulai
If then By Chtan FYHS-Kulai
Do pg.274 Ex 20b By Chtan FYHS-Kulai
Multiplication of complex numbers By Chtan FYHS-Kulai
e.g. 5 If , find the values of (i) (ii) Soln: (i) (ii) By Chtan FYHS-Kulai
If then By Chtan FYHS-Kulai
Division of complex numbers By Chtan FYHS-Kulai
If then By Chtan FYHS-Kulai
e.g. 6 Express in the form . Soln: By Chtan FYHS-Kulai
e.g. 7 By Chtan FYHS-Kulai
e.g. 8 If z=1+2i is a solution of the equation where a, b are real, find the values of a and b and verify that z=1-2i is also a solution of the equation. By Chtan FYHS-Kulai
The cube roots of unity By Chtan FYHS-Kulai
If is a cube root of 1, By Chtan FYHS-Kulai
Notice that the complex roots have the property that one is the square of the other, By Chtan FYHS-Kulai
let So the cube roots of unity can be expressed as By Chtan FYHS-Kulai
If we take then or vice versa. By Chtan FYHS-Kulai
(1) As is a solution of (2) As is a solution of By Chtan FYHS-Kulai
(3) (4) (5) … etc By Chtan FYHS-Kulai
e.g. 9 Solve the equation . By Chtan FYHS-Kulai
e.g. 10 By Chtan FYHS-Kulai
Soln: By Chtan FYHS-Kulai
Do pg.277 Ex 20c By Chtan FYHS-Kulai
The (r,θ) form of a complex number By Chtan FYHS-Kulai