<< Chapter < Page Chapter >> Page >

Mathematics

Estimations, equations and variables

Educator section

Memorandum

21. (a)

Days ___ ___ ___ ___ 5 ___ ___ 49
Bo x es ___ ___ 150 200 ___ 600 1 750 ___

22.

(b)

Sketch ___ ___ ___ ___ ___ ___
Number of squares 4 7 10 13 25 40

(c) Squares = 1 + (Sketch No. x 3)

(d) (i) 1 + (25 x 3) = 76

  1. 1 + (37 x 3) = 112
  2. 1 + (101 x 3) = 304

(e) (i) 43

  1. 55
  2. 80

23. (a) u = {} i ÷ 4

(b) u = ( i x 2) + 1

24. (a) Input

money

24. (a) Input money R1 R5 R30 R50 R100
Output : flower bulbs 3 15 90 150 300

(b)

InputNights 1 7 10 15 31
Output Cost R280 R1 960 R2 800 R4 200 R8 680

(c)

InputKg 1 4 19
OutputAmount R6,20 R17 R27,70 R35,70 R129,78

Leaner section

Content

Activity: estimations, equations and variables (algebraic equations) [lo 2.1, lo 2.3.3, lo 2.2, lo 2.4]

21. Let us see if we can formulate rules to solve equations by looking at patterns.

Every day the Cape Market purchases 50 boxes of grapes

from a farmer.

a) Complete the following table:

Days 1 2 3 4 12 35
Boxes 50 100 250 2 450

b) We can check if you are correct by writing an algebraic equation

for the above:

b (boxes) = d (days) ´ 50

Therefore: c = 3 ´ 50

= 150 (3rd day)

c = d ´ 50

250 = d ´ 50

250 ÷ 50 = d

5 = d

On day 5 the market had already bought 250 boxes of grapes.

c) Work with a partner and check the rest of your work in the same way.

22. Examine the following three sketches:

a) Can you explain to a friend the pattern that is formed here?

b) Complete this table:

Sketch 1 2 3 4 8 13
Number of squares

c) Can you write down the equation by which you can determine your solution?

_____________________________________________________________________

d) Use your equation to determine the number of squares in

(i) sketch 25: ___________________________________________________

(ii) sketch 37: ___________________________________________________

(iii) sketch 101: ___________________________________________________

e) Which sketches will contain the following number of squares?

(i) 130: _________________________________________________________

(ii) 166: _________________________________________________________

(iii) 241: _________________________________________________________

23. Are you able to write a rule (an algebraic equation) for the relationship between the input and output numbers in the following table?

a)

Input (i) 16 28 48 60
Output (o) 4 7 12 15

b)

Input (i) 105 115 125 135
Output (o) 211 231 251 271

24. Compile tables for the following (You may use your pocket calculator):

a) Flower Pot Nursery sells flower bulbs at 3 for a rand. Indicate in your table how many bulbs would be sold for R1,00 ; R5,00 ; R30,00 ; R50,00 and R100,00.

b) The Good Rest Holiday Resort's tariff is R280,00 per person per night. Indicate in your table the cost for one person for the following number of nights: 1 ; 7 ; 10 ; 15 ; 31.

c) At Sally's Supermarket you can buy grapes at R6,80 a kilogram. Indicate in your table how much you would pay for: 1 kg ; 2 ½ kg ; 4 kg ; 5¼ kg ; 19 kg grapes.

25. Time for Self-Assessment

  • Make a cross on the scale of 1 to 5 for each of the following:
Struggling So-so Capable
1 2 3 4 5
I can determine output numbers from a flow diagram correctly __ __ __ __ __
I can determine input numbers from a flow diagram __ __ __ __ __
I understand the replacing of numbers with letters of the alphabet. __ __ __ __ __
I understand what "variables" are. __ __ __ __ __
I understand the replacing of letters of the alphabet with numbers. __ __ __ __ __
I can write algebraic equations for given number sentences. __ __ __ __ __
I can resolve algebraic equations. __ __ __ __ __
I can write number sentences by making use of inequalities. __ __ __ __ __
I am able to formulate rules for solving equations by looking at patterns and can write down equations for them. __ __ __ __ __
I can compile tables from given information. __ __ __ __ __

Module test

Let us see if we can apply all the previous knowledge.

1. Just write down the answer:

a) 43 = __________ b) 93 = __________ (2)

2. True or false?

a) 125 is a cubed number ________________

b) 125 is a square number ________________

c) v – w = w – v ________________

d) (g + h) x j = (g x j) + (h x j) ________________ (4)

3. If m = 16 ; n = 9 and p = 18, calculate:

a) (m x n) + p ___________________________________

b) p ¸ n x m2 ___________________________________ (2)

4. Write an algebraic equation for the following:

a) If I subtract 347 from a number, the answer is 1706.

______________________________________________ (1)

b) The product of a certain number and 598 is equal to the difference between 80 000 and 6 446

______________________________________________ (2)

5. Write number sentences by using inequalities:

a) One quarter of the red shoes is less than half of the green shoes.

______________________________________________ (1)

b) Everyday more than 100 000 people read the newspaper.

______________________________________________ (1)

6.1 Write an equation for the following table:

Input 5 10 15 20 25 30
Output 28 53 78 103 128 228 328

______________________________________________ (1)

6.2 Use the equation to complete the table. (3)

7. Compile a table for the following:

At the Happy Fruit Stall you can buy 1 kg of apples for R6,99. In your table, indicate the cost of 2 and a half kg ; 8 kg ; 13 kg (3)

20

Assessment

Learning Outcome 2: The learner will be able to recognise, describe and represent patterns and relationships, as well as to solve problems using algebraic language and skills.

Assessment Standard 2.2: : We know this when the learner describes, explains and justifies observed relationships or rules in own words;

Assessment Standard 2.3: We know this when the learner represents and uses relationships between variables in order to determine input and/or output values in a variety of ways using:

2.3.3: tables;

Assessment Standard 2.4: We know this when the learner constructs mathematical models that represent, describe and provide solutions to problem situations, showing responsibility toward the environment and the health of others (including problems within human rights, social, economic, cultural and environmental contexts).

Questions & Answers

Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
What is specific heat capacity
Destiny Reply
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Mathematics grade 7. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11075/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Mathematics grade 7' conversation and receive update notifications?

Ask