Algebra

This Unit is about Algebra as studied in Primary Four Mathematics.

WEEK TWO

Collecting like terms

  1. Collect like terms:      4x + 8y + 2x + 5y

=     (4x + 2x) + (8y + 5y)

=     6x + 13y

  1. Collect like terms:      9m + 7n – 2m – 3n

=    (9m – 2m) + (7n – 3n)

=    7m + 4n

 

WEEK THREE

Substitution

Substitution means to replace:

  1. If x = 3, y = 4 and z = z = 5, Find the value of

=        x + y + z

=        (3 + 4) + 5

=        7 + 5

=        12

 

  1. If h = 12, find the value of 5h

5h means    5 x h

=        5 x 2

=        10

  1. If a = 5, y = 4, find the value of ay

y

 

WEEK FOUR

Solving equations involving addition

  1. Find the missing number

x +    3       =        9

x +    3-3    =        9 – 3

=        6

:.        The missing number is 6

 

  1. Solve for k

K + 4           =        9                          If 3 + m = 8

K + 4-4        =        9 – 4                     What is m?

K                 =        5                             3  +  m        =        8

3 – 3 + m     =        8 – 3

m     =        5

 

Forming and solving equations with addition

Wamala had some books. He got 3 more books. Altogether he had 7 books. How many books did he have before?

8 – 159

Let the books he had be x.

x  +  3         =        7

x  +  3-3      =        7 – 3

x                 =        4

:.        He had 4 books. 

WEEK FIVE

Equations involving subtraction

  1. If            f – 4     =   6,     Find the value of f

f – 4     =   6,

f – 4+4 =   6+4

f =   10

:. The value of f is  10.

  1. Solve for m:

m – 3           =        2

m – 3+3       =        2+3

m                =        5

 

Forming and solving equations with subtraction

Mulloli had some goats. When he sold them he remained with 9 goats. How many goats had he before?

Let the number of goats he had be g.

g  –  5          =        9

g  –  5 + 5    =        9 + 5

g                 =        14

:.   He had 14 goats. 

Equations involving multiplication

  1. If            y x  3    =    12,             What is in y?

y x  3    =        12                           OR;             y  x  3          =        12

y x  3÷3  =        12÷3                                        y  x  3/3      =        12/3

y x  1       =        4

=        4                                                            y       =        4

y is  4

 

  1. If 3P       =        21, Find P

3P      =        21

3P      =        21

3                3

P        =        7

Forming equations with multiplication

There are 4 groups in a class. Each group has the same number of pupils. Altogether there are 40 pupils. How many pupils are in each group?

Let the pupils in each group be c.

4 x c  =        40

4c      =        40

4                 4

C       =        10

:. Each group has 10 pupils.

WEEK SEVEN

Equations involving division

  1. If           n ÷ 2     =        4,       What is in the box?

n ÷ 2     =        4

n ÷ 2×2  =        4×2

n ÷  1      =        8

n   =        8

n is 8

  1. Solve for x:

x  ÷    3        =        6

x                 =        6

3                           1

x x 3            =        3 x 6

3                           1

x         =        18

 

  1. a/2    =        3

a × 2  =        3 × 2

2                 1

a x 1  =        2 x 3

a        =        6

 

Forming equations involving division

Nakandi had some balls.

She divided them into 4 groups. If there were 12 balls in each group, how many balls did she have altogether?

Let the balls she had be b.

b ÷ 4           =        12

b ÷ 4 x 4      =        12 x 4

b                 =        48

She had 48 balls altogether.

WEEK EIGHT

Equations involving more than one operation

  1. Solve for y.                                             2.  Solve for m

2y + 5     =        17                                            3m – 9     =  12

2y + 5- 5 =        17-5                                        3m – 9+9 = 12 + 9

2y           =        12                                            3m           =  21

2y           =        12                                            3m           =  21

2                      2                                                    3                3

y             =        6                                              m             =  7

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