PPT Maths Algebra - Using Letters to Represent Numbers - add n subtract.pdf
- 1. ALGEBRA Using Letters to Represent Numbers
- 2. Warm Up Activity Students, can you answer these questions? • Mary is 5 Years old. How old will she be 4 years from now? 5 + 4 = 9 • What is 7 less than 11? 11 – 7 = 4
- 3. Using Letters to Represent Numbers ADDITION • Ryan has some pencils. Ben has 5 more pencils than Ryan. Use the letter x to represent the number of pencils Ryan has. Write an expression in terms of x for the number of pencils Ben has. x Ryan 5 Ben ? x + 5 • So, Ben has x + 5 pencils. x + 5 is an example of an Algebraic Expression in terms of x Is x + 5 the same as 5 + x ? YES
- 4. Algebraic Expression can be used in other operations (addition, subtraction, multiplication and division) Algebraic Expression in Addition • Add 0 to 6 is 6 + 0 = 6 • Add 0 to x is x + 0 = x • Sum of 11 and 3 is 11 + 3 = 14 • Sum of n and 3 is n + 3 • 4 more than 8 is 8 + 4 = 12 • 4 more than y is y + 4
- 5. SUBTRACTION • Tom has 5 cookies. He gives y cookies to his friends. How many cookies does he have left? 5 – y cookies • 5 – y is another example of an Algebraic Expression • Is 5 – y the same as y – 5 ? No Algebraic Expression in Subtraction • Subtract 3 from 7 is 7 – 3 = 4 • Subtract 3 from a is a – 3 • 1 less than 12 is 12 – 1 = 11 • 1 less than x is x – 1
- 6. How to describe Algebraic Expression • Describe the Algebraic expression x + 6 as many ways as you can! Add 6 to x The sum of x and 6 6 more than x • Describe the Algebraic expression 4 + k as many ways as you can! Add k to 4 The sum of 4 and k k more than 4 • Describe the Algebraic expression n - 7 as many ways as you can! Subtract 7 from n 7 less than n • Describe the Algebraic expression 8 - m as many ways as you can! Subtract m from 8 m less than 8
- 7. EXERCISES • go to Textbook P.8 try 1A and 1B • go to Textbook P.10 Try 2A and 2B