Algebra Year 7
Algebra Year 7
ALGEBRAIC EXPRESSIONS
3(x – 8)
is
3x + (-24) or 3x - 24
-2x + 5x – 9 + 10
is
3x + 1
4x + 12
is
4(x + 3)
S Survey
P Parentheses
C Catch & Combine
= ...in equations...
A Clear Add/Subtract
D/M Clear Division/Multiplication
Name
Period
Simplifying Algebraic Expressions by Combining Like Terms + C
Objective: Students will identify like terms.
Students will simplify algebraic expressions by combining like terms.
You CANNOT
add/subtract unlike
terms.
1
2
For each algebraic expression, identify the number of terms. Then list the
coefficients and any constant terms.
6a + 3 6a – 3 0.2x – y + 8z ½n
Expression
Number of Terms
Coefficient(s)
Constant(s)
Identify the number of terms, the coefficients, and the constant term of the
expressions below.
1. 7p – 6pc + 3c - 2
Number of terms:
Coefficients:
Constant terms:
2. 8 + 4ab - 5b
Number of terms:
Coefficients:
Constant terms:
3
To simplify by combining like terms: + C
1. Search for like terms (same variable raised to the same power; and constants
with other constants).
1) 4x + 5x + 7 + x + 2 2) 2n + 3 – 5n + 6
3) - 9b + 2n – 4 + 2b 4) -7g + 3 – 8 – 3g + 7h
5) -8 + 2d – 7 – 5d + 12 6) 5b + 7 – 3b – 4
4
Identify the number of terms, the coefficient(s), and the constant HOMEWORK
term(s) of the expressions below.
1. 6p – 7pc + 9c – 4 2. 3 + 4ab - 5b + m
+ C
Coefficients: Coefficients:
4. Add. 2a + 8 + 4b + 5 5. Add. 8x – 7 + 6x + 8
5
Variable A symbol used to represent an
unknown amount.
6
Expanding Algebraic Expressions (The Distributive Property) day 1
Objective: Students will simplify algebraic expression using the distributive property.
a. 2(3x) = b. -2(3d) =
c. 5(n) = d. -3y(4) =
e. a•t= f. b(y) =
g. 3c(b) = h. 2n(4x) =
But what happens when you have more than one term inside the
parentheses?
7
Examples: 2(n + 4) 3(x – 8)
8
The Distributive Property x P (clear Parentheses)
Examples:
9
xP
1. 5(x + 3) b. 2(x + 1) c. 4(x + 5)
9
HOMEWORK xP
pg. 10
Expanding Algebraic Expressions (The Distributive Property) day 2
1 1 1
4. (10) 5. (12) 6. (9)
2 2 3
1 1 1
7. (16) 8. (6x + 10) 9. (8x − 4)
4 2 2
1 1
10. (12x + 9) 11. (15x − 3) 12. 5(2x + 1 – n)
3 3
Remember!
pg. 11
ERROR ALERT!
Some addition and subtraction problems look very similar to distributive property
problems.
1. Circle the problems that require the distributive property. Put an X through
those that do NOT require the distributive property.
YES NO
-3(x + 1) -3 + (x + 1)
pg. 12
Use the Distributive Property to expand each expression.
xP
Ex. -4(2n + 5)
1 3
− (8x + 12) (8x - 12)
g. ½(4x – 6) h. 4 i. 4
pg. 13
HOMEWORK
Expand the expressions that require the distributive property.
Put an X through the expressions that do not require the distributive property.
REMEMBER—you can only distribute (multiply) over addition or subtraction!
1 1
(9n + 15) (6b − 10)
10. -4(n 5) 11. 3 12. 2
pg. 14
Simplifying Algebraic Expressions by Distributing
and Combining Like Terms
pg. 15
S
Simplifying Algebraic Expressions by Distributing P
and Combining Like Terms C
=
A
Objective: Students will simplify algebraic expressions by combining like D/M
terms.
A. Simplify the expressions below (Hint: ONE of them needs dist. property).
a. 2x + 5 + (6x + 1) b. 2x + 5 + 6(x + 1)
B. Sometimes you will need to CATCH the term (including a subtraction sign)
before you distribute.
pg. 16
Simplify. (Ask… Do I need to distribute? If so, do it FIRST!)
S
1. 3(x + 6y – 7) P
C
=
A
D/M
2. -7(2x – 4)
3. 4(3x + 7) - 5x
4. 3x - 2(-4x + 5)
pg. 17
S
Extra Practice
P
Rewrite the expressions without parentheses. C
(Hint: check for dist. property first!) Then simplify. =
A
1. 8 + (2x – 1)7 2. -3(3x – 5) + 8x D/M
pg. 18
S
HOMEWORK
P
Simplify. C
=
1a. -3(2x – 3y - 5) 1b. -4(2y - 3) + 7y
A
D/M
4. For each algebraic expression, identify the number of terms. Then list the
coefficients and any constant terms.
Expression 8x - 3 4x + y + 11
Number of Terms
Coefficient(s)
Constant(s)
pg. 19
Simplifying Algebraic Expressions by Distributing
and Combining Like Terms
x P
1.a 3(x + 6y – 7) 1.b. -7(2x – 4)
3a. 5x + 6y – 4x + 3y – 9 3.b. - 9x + 7 –x + 5x - 4y
pg. 20
HOMEWORK
1. 7(2x – 1) + 8 2. -3(3x – 5) + 8x
5. 12y + 7(2y – 3)
pg. 21
Adding and Subtracting Algebraic Expressions
pg. 22
Note the difference between the two problems below.
Which problem requires the distributive property to simplify it?
pg. 23
c. Distribute the -1 d. Distribute the -1
pg. 24
HOMEWORK
1. Distribute the -1
(6h + 4) – (2h + 3) x P
+ C
2. Distribute the -1
(6h + 4) – (2h - 3)
3. Distribute the -1
(6h - 4) – (2h - 3)
pg. 25
Factoring Algebraic Expressions
Objective:
pg. 26
Ex 1. Factor. 14xy + 21x
To factor an algebraic expression you use division to undo the distributive property.
1. Make the “skeleton” of a distributive property problem under the given one.
It will look like this: ( + ) or ( - ) this.
2. Look for a variable that is shared by the terms (they may share more
than one); circle it and then place the shared variable on the outside,
next to the parentheses.
4. Find the GCF of the coefficients. (Check to see if the smallest # you see is a
factor of the others. If so, it’s the GCF. Otherwise, use the “rainbow” method.)
5. Place the GCF on the outside of the parentheses. If there are any
letters already there, the GCF will become their coefficient.
6. Divide the 1st term by the GCF you found. Place the quotient on the line.
7. Divide the 2nd term by the GCF you found. Place the quotient on the line.
Ex 2. 12x + 6
pg. 27
Ex. 3 5b – 15n Ex. 4 3n – nj
2. 8y - 12y Check:
3. 8n – 2 Check:
4. 14z + 21 Check:
Check:
5. 4h - 12
pg. 28
6. 8a + 4 Check:
9. 9n + 7n Check:
pg. 29
HOMEWORK
1. Write the factored form of each expression.
2. Check using distributive property.
a. 18a + 3 Check:
Check:
b. -2c + 6d
Check:
c. 20xy + 10x
Error analysis: Ali factored the above problem, c, and got 2x(10y + 5). When
she checked it using the distributive property, she got the original problem! Since
her check worked, she thinks she has the correct answer. How can that be?
Explain her mistake.
3. Error analysis: Jamie incorrectly factored 15x – 20xy. She got 5x(3 – 4xy).
Factor the expression correctly.
1. 24xy + 10x
2. 15m – 18mn
3. 4x – xy
4. 42x + 7y
5. 4x – 2xy
6. 32xyz + 12xy
pg. 31
pg. 32
Indices part 1
In this chapter, you are going to
•
• Learn about negative indices
• Learn about fractional indices
• Use fractional indices to evaluate square roots and cube roots
Recap
1. Numbers written in index form
81 = = 34 Index form
3×3×3×3
Expanded form
2. Multiplication law
𝒂𝒎 × 𝒂𝒏 = 𝒂𝒎+𝒏
Examples:
(a) 𝒂𝟑 × 𝒂𝟐 = 𝒂𝟑+𝟐 = 𝒂𝟓
(b) 𝟒𝟓 × 𝟒𝟐 = 𝟒𝟓+𝟐 = 𝟒𝟕
(c) 𝟑𝒂𝟑 × 𝟐𝒂𝟐 = (𝟑 × 𝟐)𝒂𝟑+𝟐 = 𝟔𝒂𝟓
3. Division law
𝒂𝒎
𝒂𝒎 ÷ 𝒂𝒏 = = 𝒂𝒎−𝒏 , 𝒂 ≠ 𝟎
𝒂𝒏
Examples
(a) 𝒂𝟓 ÷ 𝒂𝟐 = 𝒂𝟓−𝟐 = 𝒂𝟑
𝟑𝟕
(b) 𝟑𝟐 = 𝟑𝟕−𝟐 = 𝟑𝟓
𝟏𝟐𝒎𝟓 𝟏𝟐 𝟓−𝟒 𝟏
(c) = ( 𝟑 )𝒎 = 𝟒𝒎 or simply 𝟒𝒎
𝟑𝒎𝟒
4. Power law
(𝑎𝑚)𝑛 = 𝑎𝑚𝑛
Examples
5. Meaning of 𝒂𝟎
𝒂𝟎 = 1
Examples
(a) 𝑚0 = 1
(b) 30 = 1
(c) 3𝑚0 = 3
(d) 𝑏 5 ÷ 𝑏5 = 𝑏 0 = 1
So far we have done a recap of the various laws of indices you have learned in
grade 7. Now we are going to learn some more laws and rules of indices in
grade 8.
(𝒂𝒃)𝟑 = 𝒂𝟑𝒃𝟑
Similarly
𝒂 𝟐 𝒂 𝒂 𝒂×𝒂 𝒂𝟐
( ) = ( )×( ) = =
𝒃 𝒃 𝒃 𝒃 × 𝒃 𝒃𝟐
We conclude that
𝒂𝟐 𝒂𝟐
( ) =
𝒃 𝒃𝟐
Rule 1 :
Rule 2:
𝒂 𝒏 𝒂𝒏
Examples
Simplify the following:
(a) (2𝑚)3
(b) (3𝑝)2
(c) (2𝑚)0
(d) 2(𝑚𝑛)0
Solutions:
(a) (2𝑚)3 = 23𝑚3 = 8𝑚3 ( according to rule 1, the power 3 belongs to both 2 and 𝑚 )
(b) (3𝑝)2 = 32𝑝2 = 9𝑝2 ( according to rule 1, the power 2 belongs to both 3 and 𝑝 )
(c) (2𝑚)0 = 20𝑚0 = 1 × 1 = 1 since (2𝑚)0 = 1
(d) 2(𝑚𝑛)0 = 2 × 𝑚0 × 𝑛0 = 2 × 1 × 1 = 2 since 2(𝑚𝑛)0 = 2
2 2 22 4
(e) ( ) = 2 = 2 ( according to rule 2, the power 2 belongs to both 2 and 𝑝 )
𝑝 𝑝 𝑝
2𝑚 2 22𝑚2 4𝑚2
2. Negative indices
𝟏
𝒂−𝒙 =
𝒂𝒙
Examples
Evaluate the following:
(a) 5−2
(b) 2−3
(c) 4𝑦−3
(d) 3𝑚−2
(e) 𝑎−3 × 𝑎−2
(f) (23)−2
Solutions
1 1
(a) 5−2 = =
52 25
1 1
(b) 2−3 = =
23 8
1 4
(c) 4𝑦−3 = 4( ) = 𝑦3
𝑦3
1 3
(d) 3𝑚−2 = 3 ( )=
𝑚2 𝑚2
1
(e) 𝑎−3 × 𝑎−2 = = 𝑎−5 = 𝑎−3+−2 𝑎5
34 1 1
(d) = 34−7 = 3−3 = =
37 33 27
1 1
(f) (23)−2 = 2−6 = =
26 64
3. Power law involving fractional indices.
𝟏 𝟏
Examples
Evaluate the following:
1
(a) (23)3
1
(b) (54)2
1
(c) 273
2
(d) 1253
2
(e) 80003
Solutions
1 1
(a) (23)3 = 23×3 = 21 = 2
1 1
(b) (54)2 = 54×2 = 52 = 25
1 1
(c) 27 =3 33×3 = 31 = 3
2 2
(d) 1253 = 53×3 = 52 = 25
2 2 2 2
(e) 80003 = (26 × 53)3 = (26)3 × (53)3 = 23×2 × 52 = 16 × 25 = 400
Exercises for practice
1. Simplify the following.