algebra basics for third form

1. Algebra
Grade 9
Mrs. N. Wilson

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2018
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3. − 2 = 4
− 2 = 6
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2018
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4. What is Algebra?
Algebra is the use of letters and
symbols to represent values.
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2018
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5. Algebraic Expressions
This is a
combination of
one or more
terms.
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2018
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Examples:
3𝑚 + 2
𝑥2 + 4𝑥 + 4
12 + 𝑏
3𝑚 + 6𝑛 − 6

6. Term
This is the name given to a number, a
variable or a number and variable
combined by multiplication or division
within an algebraic expression.
Example:
1. 𝑎 + 2 ,the terms are a and 2
2. 3𝑚 + 6𝑛 − 6 ,
the terms are 3m, 6n and -6.
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2018
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7. Question
What are the terms in the expressions
below?
1. 3x + 4
2. a × 2b ÷ b
3. 24z – 16z
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2018
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8. Numerical Coefficient
This is the number by which a variable
is multiplied.
Example: Given 8x, the coefficient of x
is 8.
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2018
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9. NOTE:
If there is no coefficient before the
variable then the coefficient is
considered to be 1.
Example: Given x, the coefficient of x
is 1.
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2018
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10. Variable
This is an unknown value that is usually
represented using a symbol or a letter
of the alphabet.
Example: Given 9a, a is the variable of
9a.
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11. Constant
This is a number that cannot change its
value.
Example:
In the expression 5𝑥 + 7𝑦 − 2, the
constant is -2.
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2018
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12. Activity
Use the following terms to identify
each part of the expression below:
Numerical coefficient, variable and
constant
9x + 4
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2018
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13. Sub-topic:Translating Sentences
into Algebraic Expression
This is to re-write a given sentence using
algebraic terms.
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2018
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14. Key terms to note when
translating
Operation Key terms/phrases Examples
Addition 1. Added to
2. Increased by
3. More than
4. The sum of
5. The total of
6 more than a number
Let the unknown
number be x
6 + x
Subtraction 1. Less than
2. Minus
3. Decreased by
4. Less
5. Subtracted from
34 decreased by a
number
34 - x
Division 1. Quotient of
2. Divided by
3. The ratio of
The quotient of 9 and
a certain number
9 ÷ x
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15. Terms Cont'd
Operation Key terms/ phrases Examples
Multiplication 1. Multiplied by
2. Product of
3. Twice; double
4. Times
The product of 12 and
a number
12 × x or 12x
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16. Now it’s your turn!
In your groups attempt to rewrite the
following sentences into expressions.
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17. Questions:
1. A number decreased by 11
2. 5 more than a number
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18. Cont’d
3. A number divided by 7
4. The product of p and q.
5. 4 times the sum of 1 and a number d
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19. Worded question
Yuri is 8 years old. Raymond is two-
and-a-half times as old as your. Write
an algebraic expression for Raymond's
age?
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20. Individual Work!
1. 7 subtracted from x
2. The quotient of x divided by 7
3. If Martin’s m kilograms, represent
his mass after he gains 7 kilograms.
4. Stacey is x years younger than her
sister who is 15 years older. Express
Stacey’s age algebraically.
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