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What is variance?? A measure of spread that takes all values into account. What is the mathematical definition of variance, in words?? The average squared distance from the mean. What is the formula for variance?? $$ \sigma^2 = \frac{\sum (x - \bar{x}) ^ 2}{n} $$ Or $$ \sigma^2 = \frac{\sum x^2}{n} - \bar{x}^2 $$ What is the definition of the standard deviation?? The average distance from the mean. What is the formula for standard deviation?? $$ \sigma = \sqrt{\sigma^2} $$

Measures Measures are a set of summary statistics, a set of values to describe data. Measures of Location Maximum Minimum Quartiles Percentiles Deciles Measures of Centeral Tedency Mode Median Mean Measures of Spread Range Standard Deviation Interquartile range Variance When comparing data sets, what two things do you need to comment on?? A measure of location A measure of spread When comparing data sets, what measure of spread could you comment on?

What is uniform acceleration?? Where the acceleration is constant during motion. What is non-uniform acceleration?? Where the acceleration changes during motion. Vector’s quote in Dispicable Me is?? “I commit crimes with both direction and magnitude” Mass is a vector/scalar quantity?? Scalar. Energy is a vector/scalar quantity?? Scalar. Velocity is a vector/scalar quantity?? Vector. Speed is a vector/scalar quantity?? Scalar. Displacement is a vector/scalar quantity?? Vector. Distance is a vector/scalar quantity?? Scalar. How could you describe the velocity of a object moving at a constant speed in a circle?

Forces What is the weight of an object?? The force acting vertically downwards. What is the normal reaction?? The force acting perpindicular from a surface when an object is in contact with the surface. What is the normal reaction the same as?? The weight of an object on a surface. What is the name of the force acting perpindicular from a surface on an object resting on the surface?? The normal reaction. What is friction?? The force which opposed the motion between two rough surfaces.

Models What is a model?? A model is a simplified representation of a physical situation, made by accepting assumptions. What’s an example of a common assumption?? No air resistance Constant gravity Uniform mass What two questions need to be asked when setting up a mathematical model?? What are your assumptions? What are the variables? If the answer presented by a mathematical model is unreasonable, what should be done?? You should reconsider your assumptions.

Boolean Algebra Boolean algebra is like writing algebraic expressions acting on variables. Boolean notation is the set of symbols that define logical operators on variables. $$ P = \text{NOT} (A \text{AND} B) P = \overline{A \cdot B} $$ $$ P = (A \text{AND} B) \text{OR} C P = (A \cdot B) + C $$ NOT $$ P = \text{NOT} A P = \overline{A} $$ What does the notation $\overline{A}$ in boolean algebra?? NOT. AND $$ P = A \text{AND} B P = A \cdot B $$

Conjugates A pair of complex numbers with a different sign but otherwise the same values are called conjugates: $$ 3 + 4i 3 - 4i $$ What are complex conjugates?? A pair of complex numbers with real and imaginary parts equal in magnitude but opposite in sign: $a+bi$ and $a-bi$ What is a pair of complex numbers $a+bi$ and $a-bi$ called?? A complex conjugate. What is the result of multipling complex conjugates?? You get a real number.

Logic Gates Name Shape AND Like a “D” OR Like a crescent NOT Like a triangle with a dot NAND Like and with a dot NOR Like an OR with a dot XOR Like OR with an extra crescent AND Input 1 Input 2 Output 0 0 0 0 1 0 1 0 0 1 1 1 OR Input 1 Input 2 Output 0 0 0 0 1 1 1 0 1 1 1 1 NOT Input 1 Output 0 1 1 0 NAND AND + NOT

Computing Syllabus Link to specification: https://filestore.aqa.org.uk/resources/computing/specifications/AQA-7516-7517-SP-2015.PDF Entries [[Computing - Operating Systems]]S [[Computing - Logic Gates]]S [[Computing - Boolean Algebra]]S [[Computing - Hardware and Software]]S [[Computing - Translators and Machine Code]]S [[Computing - Libraries]]S [[Computing - Programming Languages]]S [[Computing - Little Man Computer]]S [[Computing - Computer Organisation and Architecture]]S [[Computing - Harvard vs Von Neumann Architecture]]S [[Computing - AQA Assembly]]S [[Computing - Queues]]S [[Computing - Data Representation]]S [[Computing - Binary]]S [[Computing - The Processor]]S [[Computing - Images]]S [[Computing - Sound]]S [[Computing - MIDI]]S [[Computing - Compression]]S [[Computing - Encryption]]S [[Computing - Number Systems]]S [[Computing - Stacks]]S [[Computing - Hash Tables]]S [[Computing - Graphs]]S [[Computing - Trees]]S [[Computing - Vectors]]S [[Computing - SQL]]S [[Computing - Databases]]S [[Computing - Input & Output Devices]]S [[Computing - Object Oriented Programming]]S [[Computing - Finite State Machines]]S [[Computing - Sets]]S [[Computing - Regular Expressions]]S [[Computing - Regular Languages]]S [[Computing - Turing Machines]]S [[Computing - Reverse Polish Notation]]S [[Computing - Backus-Naur Form]]S [[Computing - Parsing]]S [[Computing - Syntax Diagrams]]S [[Computing - Networking]]S [[Computing - Communication]]S [[Computing - Topologies]]S [[Computing - WiFi]]S [[Computing - Cloud Computing]]S [[Computing - Thick and Thin Clients]]S [[Computing - Social and Legal Challenges]]S [[Computing - Structure of the Internet]]S [[Computing - Network Hardware]]S [[Computing - TCP/IP Stack]]S [[Computing - Client/Server Model]]S [[Computing - Functional Programming]]S [[Computing - Big Data]]S [[Computing - Recursion]]S [[Computing - Searching Graphs]]S [[Computing - Limits of Computation]]S [[Computing - Abstraction]]S Syllabus Fundamentals of Programming Programming Data Types Programming Concepts Operations Constants and Variables String-Handling Random Number Generation Exception Handling Subroutines Recursion Programming Paradigms Procedural-oriented programming Object-oriented programming Fundamentals of Data Structures Data Structures and Abstract Data Types Data Structures Arrays Fields, Records and Files Abstract data types/data structures Dictionaries Fundamentals of Algorithms Graph-traversal Tree-traversal Reverse-polish notation Searching Algorithms Sorting Algorithms Optimisation Algorithms Theory of Computation Abstraction and Automation Problem-solving Following and writing algorithms Abstraction Information hiding Procedural abstraction Functional abstraction Data abstraction Problem abstraction Decomposition Composition Automation Regular languages Finite state machines Regular expressions Regular language Context-free languages BNF, Syntax Diagrams Classification of Algorithms Big-O notation Limits of computation Computable and non-computable problems Halting Problem A Model of Computation Turing Machines Data representation Number bases Units of information Bits and bytes Units Binary Unsigned binary Signed binary Binary and fractions Information coding systems ASCII and Unicode Error checking and correction Sound Midi Images Bit patterns Analogue and digital Graphics Bitmapped graphics Vector graphics Compression Encryptions Fundamentals of computer systems Hardware and Software Operating Systems Programming Languages Translators and Machine Code Logic Gates Boolean Algebra Computer Organisation and Architecture Harvard vs Von Neumann Architecture Internal hardware components of a computer The stored program concept Structure and role of the processor External hardware devices I/O devices Secondary storage devices Consequences and uses of computing Moral, social, legal and cultural issues Fundamentals of communication and networking Communication Networking The Internet TCP/IP Protocol Fundamentals of databases Data models and entity relationship modelling Relational databases Database design SQL Client server databases Big Data Fundamentals of functional programming Function Type First-class Objects Functional application Composition of functions Writing functional programs Lists in functional programming Systematic approach to problem solving Aspects of Software Development Analysis Design Implementation Testing Evaluation NEA Info This page was last updated on 2022-02-21.

What is the role of an operating system?? Hide the complexities of the hardware from the user. Where is the OS stored on a computer?? On the hard drive. How is the BIOS stored?? On the ROM. What is ROM?? Read only memory. How is the OS loaded when the computer is switched on?? The bios. What is a virtual machine?? A layer of software that allows one computer to simulate another and to run more than one operating system.

Here, using $z$ instead of $x$ means that the variable is complex. $w$ is also sometimes used. The first step is to find the one real solution. Since it’s a cubic, there will be three solutions and by examining the graph you can see that there always must be at least one real solution (cubics always cross the $y$-axis at least once). For $z = 1$: $$ z^3 + 9z^2 + 33z + 25 1^3 + 9\times1^2 + 33\times1 + 25 \neq 0 $$