Complex Numbers and Applications
ME50 ADVANCED ENGINEERING MATHEMATICS
1 Complex Numbers √ A complex number is an ordered pair (x, y) of real numbers x and y. For example, (−2.1, 3.5), (π, 2), (0, 0) are complex numbers. Let z = (x, y) be a complex number. The real part of z, denoted by Re z, is the real number x. The imaginary part of z, denoted by Im z, is the real number y. Re z = x Im z = y Two complex numbers z1 = (a1, b1) and z2 = (a2, b2) are equal, written z1 = z2 or (a1, b1) = (a2, b2) if and only if a1 = a2 and b1 = b2. For example, if (x, 2) = (3, c) then x = 3 and c = 2. Since a complex number is denoted by an ordered pair (x, y) of real numbers x and y, then we may view the complex number (x, y) as the point with abscissa x
…show more content…
1. z = z 2. (cz) = cz 3. z1 + z2 = z 1 + z 2 4. z1z2 = z 1z 2 5. z1 z2
=
z1 z2
1.4 Forms of a complex number
The norm of a complex number z = (x, y), denoted by z is the real number z = x2 + y 2. For example, if z = (4, −3), then z = 42 + (−3)2 = 5. Observe that z is numerically equal to the distance from the point z in the complex plane to the origin (0, 0). A complex number with norm 1 is called a unit complex number. Some examples of unit complex √ √ 3 4 numbers are 5 , − 5 , (1, 0), 22 , 22 , (0, 1).
4
Of particular importance to us are the unit complex numbers (1, 0) and (0, 1). Observe that (1, 0)(x, y) = (x, y) for all complex numbers (x, y). For this reason, we simply denote (1, 0) by 1. Let us denote the unit complex number (0, 1) by i. Then i2 = (0, 1)(0, 1) = (−1, 0) = (−1)(1, 0) = −(1, 0) = −1. Therefore, i2 = −1. The reason why 1 and i are important unit complex numbers is because every complex number can be written as a linear combination of them. To see this, let z = (x, y) be any complex number. Then z = (x, y) = (x, 0) + (0, y) = x(1, 0) + y(0, 1) =x·1+y·i = x + iy The form x + iy of the complex number (x, y) is called the Cartesian form. For example, the Cartesian form of (2, −3) is 2 − 3i. Operations on complex numbers become more convenient if we write complex numbers in Cartesian form and remember that i2 = −1. For example, to multiply (2, −3) and (−1, 2), we do it this way: (2, −3)(−1, 2) = (2 −
The real number system consists of five subsets of numbers (Blitzer, 2013). The first subset is natural numbers; natural numbers consist of positive counting numbers not including zero. The second subset is whole numbers; whole numbers consist of zero and natural numbers. The third subset is integers; integers are positive and negative whole numbers, as well as zero. The fourth subset is rational numbers; rational numbers are numbers that can be written in fraction form. The fifth and last subset is irrational numbers; irrational numbers are numbers that are not a perfect square, do not have a repeating or terminating decimal, and are not included in the whole numbers subset (Blitzer, 2013). Rational and irrational numbers are often the most difficult to understand out of these 5 subsets of real numbers. Simply put, rational numbers are any numbers that can be re-written as a simple fraction, and if a number cannot be defined as rational then it is defined as irrational. For example, the number 7 is a rational number because it can be re-written as , which is a simple fraction. The number 2.5 is also defined as rational because it can be re-written as , which, again, is a simple fraction. However, if the number π were defined, it would have to be irrational since it has neither a repeating decimal nor a terminating decimal, and cannot be written as a simple fraction.
Yalom (in Dadban & Rosen, 1990a) was not as directive as in the inpatient video (Dadban & Rosen, 1990b). He led the members discuss a given topic more freely than the inpatient group. In other words, the outpatient group appeared less structured compared to the inpatient group. Perhaps, it is more accurate to state that those groups were structured differently according to the group members’ level of function and needs.
We can use this information for simple division, multiplication and even when multiplying and dividing larger numbers. This information can be used when cooking, grocery shopping, building things etc..
Include expressions that arise from formulas used in real world problems. Perform arithmetic operations, including those involving whole-number exponents, in the conventional order when there are no parentheses to specify a particular order (Order of Operations).
Section A—DIRECTIONS: Each of the following statements is either true or false. Unless directed otherwise by your instructor, indicate your choice in the Answers column by writing
Determine whether each of the functions from Z to Z is one to one. (i) ( ) (ii) ( )
A new year, a fresh start, an opportunity to overhaul the habits we fall into. Year after year, folks reevaluate their lives and desire a change in how they about their day. Some decide to change their diets and eat healthier, while others decide make it to gym more frequently. Whatever the person’s attempted alteration may be, the common theme that everyone experiences a process of change. Along with this attempt at change, individuals making the change will often be challenged to return back to old habits. Although persistence shines for some, others will fall back into old habits once they experience the trade-off to abandoning a habit. Simply denoted as behavioral change, this process by which an individual
The volume of the cube is 100 cm3 more than the volume of the cuboid.
Look at these sentences. They are all incorrect. Rewrite the answers on the lines provided.
By using geometry to evade irrational numbers, a mathematical crisis had been covered. Although Greeks could not tolerate irrational numbers, they accepted “irrational geometric quantities such as the diagonal of the unit square” (Lecture 8. Eudoxus, Avoided a Fundamental Conflict), or square root
formulae? I shall keep the size of the square at a constant (2 x 2)
This technique is instead of adding the exponent like multiplication you just subtract them. For x^3/x^2 = x^1. This only works if the variables are the same. The second to last technique is the 0 power. The 0 power says that if the exponent is 0 then it will always equal 1. Finally, the last technique is if you have (x^3)^2 you multiple the exponents so it would equal x^6. Another subject I leaned in this unit is earthquakes. What I learned about earthquakes and what it has to do with math is there is a machine called ritcher scale and this calculates the power of the earthquake. This is related to math because ritcher scale is logarithmic which means the magnitudes of earthquakes is ten times stronger. For example if the magtuide is 0.1 then I would have to multiple by 10 so it would be 1. Finally, the last subject I learned in this unit is polynomial. One thing I learned is adding polynomial. How you add polynomial is for example if I had (3b+6) (5b+5), first you would do 3b+5b = 8b+5+6 = 8b+11. You would do the same following steps for subtraction. Another subject I learned is multiplying polynomial. How you multiple polynomial is for example (y+6)+(y+6), first y*y= y^2 +6*6 =
Symbolic representation using base-ten and expanded algorithms is a way to show students the written connection to the visual models used. The partial-products algorithm is a more detailed step-by-step process and therefore more advisable to avoid errors in students learning to grasp the procedure (Reys ch.11.4). This process allows students to visualise the distributive property more easily. However, the standard multiplication algorithm is quicker and acceptable for students, if the teacher feels they have complete understanding of the steps in the partial-products algorithm.
Euclid’s assumptions about his postulates have set the groundwork for geometry today. He provided society with definitions of a circle, a point, and line, etc and for 2000 was considered “the father of geometry.” His postulates proved to be a framework from which mathematics was able to grow and evolve, from two thousand years ago, till Newton and even to all our classrooms today.