Year 7 Algebraic Expressions Dr J Frost (jfrosttiffin.kingston.sch.uk) www.drfrostmaths.com Last modified: 4th May 2016 Objectives: Appreciate the purpose of algebraic variables and simplify algebraic expressions. Substitute into algebraic
"Year 7 Algebraic Expressions Dr J Frost" is the property of its rightful owner. Permission is granted to
download and print the materials on this website for personal, non-commercial use only, and to display it
on your personal computer provided you do not modify the materials and that you retain all copyright
notices contained in the materials. By downloading content from our website, you accept the terms of this
agreement.
Presentation Transcript
01
Year 7 Algebraic Expressions Dr J Frost (jfrost@tiffin.kingston.sch.uk)
www.drfrostmaths.com Last modified: 4th May 2016 Objectives: Appreciate the purpose of algebraic variables and simplify algebraic expressions.
Substitute into algebraic expressions.
Form algebraic expressions from worded information.<br>
02
Source: Google Algebra concerns representing missing information.
Put simply, we use letters, known as variables, to (usually) represent numbers.
Usually the value of variables are not initially known, but we hope to combine available information to find their value. Examples:<br>
03
Your age in 4 years time. Twice your age. A third of your age. ? ? ?<br>
04
[JMC 2008 Q18] Granny swears that she is getting younger. She has calculated that she is four times as old as I am now, but remember that 5 years ago she was five times as old as I was at that time. What is the sum of our ages now? Worded problem Stage 1: Represent problem algebraically Stage 2: ‘Solve’ equation(s) to find value of variables. These next few lessons we’ll be looking at Stage 1. Stage 2, ‘solving’, we’ll do later this year.
Being able to do these two stages for difficult problems is a vital skill for Maths Challenges/Olympiads. We won’t solve this now, but how would we approach such a problem?<br>
05
? How does this ‘simplify’? Why conceptually does it work? ? More Examples: ?<br>
06
x2 2x2 -3x2 3x3 -x3 y2 5xy2 4x2y 2x2y -1 +4 x 9x 5xy Instructions: In pairs, discuss which terms you think might be ‘like’ terms, i.e. they could be combined together into one when adding/subtracting. Therefore, terms are ‘like terms’ if:
The involve the same variables and powers. ?<br>
07
? ? ? ? ?<br>
08
?<br>
09
You should have printed the following pyramids. Each block is the sum of the two below it, e.g. as per on the right.
Can you fill in the missing blocks? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1 2 3 4<br>
10
? ? ? ? ? ? ? ? ?<br>
11
? ? ? ? ? a b c d e Simplify the following.<br>
12
? Fractions are ultimately just divisions. How did we simplify this fraction?
Can we apply the same principle to algebraic division? ? ? ? ? ? ?<br>
13
? ? ? ?<br>
14
1 Simplify the following, or write ‘already simplified’. a b c d e f g h i j 2 a c e g i j k l b d f h 3 a c e g i j b d f h k 4 a c b d ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?<br>
15
12? 36?<br>
16
Bro Tips:
Start by working out each of the terms first (mentally if you can) leaving the +/- symbols between as they are.
Don’t try to do all at once. ? ? ?<br>
17
? ? ? ? ? ?<br>
18
? ? ? ? ?<br>
19
? ? ?<br>
20
1 a b c d 2 a b c d e 3 4 a b c d e 5 6 a b c d e ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?<br>
21
[JMC 2008 Q18] Granny swears that she is getting younger. She has calculated that she is four times as old as I am now, but remember that 5 years ago she was five times as old as I was at that time. What is the sum of our ages now? Worded problem Stage 1: Represent problem algebraically Stage 2: ‘Solve’ equation(s) to find value of variables. Remember this problem? We’ll be looking how we can turn worded information into algebraic expressions.<br>
22
? ? ? ? ? ? Later this year you’ll properly learn how to ‘expand brackets’. ?<br>
23
“The sum of 5 consecutive whole numbers is 285. What is the smallest of these numbers?” Option 1 Option 2 ? ? ? ? ? ? Why might Option 2 might make the later ‘solving’ stage easier?<br>
