USE OF SYMBOL

USE OF SYMBOL

by Oluwabusayo Atteh

​RESUMPTION TEST

​For each open number sentence, find the number that makes the sentence true.

1. 17 − 9 = □​

2. 2 × 12 = □

3. 30 + 30 + ◯ = 3 × 30

​Find the value of the following expressions if x=3​​

​4. 1/x+1/x

​5. 9 − x + 2

Find the value of the variable in the following open sentences:

​6. p − 4 = −3

​7. b ÷ 20 = 5

​RESUMPTION TEST 2

​For each open number sentence, find the number that makes the sentence true.

1. 3 + 9=□

​2. 2 x □ = 24

​3. 5 + ◯ + 18 = 30

​Find the value of the following expressions if x=4.

​4. 1/x + 1/x

5.​ 9 − x + 2

​Find the value of the variable in the following open sentences:

​6. p − 4 = −2

​7. b ÷ 20 = 5

​OPEN SENTENCE

​Open sentence is a statement ( in mathematics) that contains at least one blank or unknown and that becomes true or false when the blank is filled or a quantity is substituted for the unknown

​CLOSE SENTENCE

​A closed number sentence gives all the information about the numbers, and it is always true or always false.

​

Example: 2 x 5 = 15 ( true)

Multiple Choice

Decide if the close sentence is true or false

4 x 10 = 40

• true

• false

Multiple Choice

9 ÷ 18 = 2

• true

• false

​EXAMPLE of open sentence

​14 + ​□ = 17 is an example of open sentence.

​

​CLASS ACTIVIYT 1

​EXERCISE 5a and 5b ( orally) each student pick a question and answer it in there note book,

​

Multiple Choice

3 + 2 = □

• 1

• 3

• 5

• 7

Multiple Choice

8 - □ = 2

• 2

• 4

• 6

• 8

Multiple Choice

3 x 4 = □

• 10

• 12

• 13

• 15

Multiple Choice

15 ÷ □ = 5

• 3

• 5

• 10

• 15

​CLASS ACTIVIYT 2

​EXCERCISE 5C

​QUESTION 1a, 2b and 3c

​LETTER FOR NUMBERS

​Variables in open sentences

A variable is a symbol for a number we do not know yet. It is usually a letter such as x or y.

​

​If we have an expression, such as x+5, we cannot know the value of the x unless it is given. If we give the x different values, then we can make number sentences that are true.

​let start with x = 1

CLASS WORK

Exercise

​Solving open sentences that have variables

​GENERALISED ARITHMETIC: Mathematical statements that use letters and numbers together

​

​ALGEBRA: The mathematical word for generalised arithmetic

​

​ALGEBRAIC SENTENCE: A statement with an equal sign

​EXAMPLES

​Exercise 5d : orally

​CLASS TASK

​FIND THE NUMBER THAT EACH ALPHABET STANDS FOR

​1. x = 2 + 7

​2. 19 + e = 30

​3. z - 6 = 2

​4. 5 = 4 + a

​5. v ÷ 4 = 20

​6. 28 = 7 x a

​MORE EXAMPLES

​1. x + x = 8

​2. g + g + g = 30

​3. t ÷ t = 1

​4. q x q = 4

​5. 20 - n = n

​SOLUTION

​lets solve in our note book.

​WORD PROBLEM

​Examples

1. ​A bicycle cost N10 000 and a radio cost Nx. They cost N 16 000 altogether. What is the value of x?

​2. Amina is x year old. Next yesr she will be 14 years Old. What is the value of x?

​EVALUATION QUESTION

​1. David has N80 more than Mary.

​(a) If Mary has N340, how much does David have?

​(b) IF Mary has N Naira, How much does David have.

​

​2. A Sum of N5 000 is shared equally between x girls. One of the girls spendsN360. How many naira does she have left?

​MORE EXAMPLES

​EXCERISE 5g, Question 3 and 4.

​Practise Question : Exercise 5g Question 5 to 11.

​ALGEBRA FROM WORDS

​Study figure 10.1

​Study the picture and interpret it.​

​EXAMPLE 1:

​Baba is 13 years old.

​(a) How old will he be 8 years from now?

​(b) How old will he be in y years from now?​

​

Open Ended

CLASS TASK

​(a) In a test Ada got 7 marks more than Emmanuella. Emmanuella got x marks?

​(b) Ike got y marks more than Ada. How many marks did Ike get?

​EXAMPLE 2

​ 1. A boy has m mangoes. If he eats 5 of them how many does he have left.

​2. A woma is 30 years old

​(a) What was her age 10 years ago?

​(b) What was her age y years ago?

​

​

Open Ended

CLASS TASK 2

​A booj has x pages. A boy reads 30 pages of the books. How many pages has the boy not read?

​EXAMPLE 3

​1. (a)How many days are in 1 week

​(b) How many days in 5 weeks?

​(c) How many days in w weeks?

​

Open Ended

CLASS TASK 3

What is the number that is 9 times greater than d?

​

​EXAMPLE 4

​1. Six identical blocks have a total mass of Bkg. What is the mass of each blocks?

​SOLUTION