2TH §11.5 Quadratic equations

§11.5 Quadratic equations
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This lesson contains 14 slides, with text slides.

time-iconLesson duration is: 50 min

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§11.5 Quadratic equations

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In this LessonUp .....
All that you have learnt up till now is repeated.
To help you doing the exercises from §11.5


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Solving quadratic equations
You know two methods of solving quadratic equations:
- Cards:
- Factorising:  A x B = 0, then A = 0 or B = 0
When to use which method?

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A. Solving quadratic equations with CARDS
Question 1:  Can you use cards?
(You can use cards if the equation contains only 1 variable)

Yes? Solve using cards.
No? Go to B,  for Factorising Binomials and Trinomials

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A. Solving quadratic equations with cards
Use the balance method (add/subtract the same amount, divide/multiply by the same number , take the square root on both sides of the equal sign, don't forget the second solution)

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B. Solving quadratic equations
by Factorising
Question 2: Is one side of the equation equal to 0?

Yes?  
See examples next slide. We only factorise,
soon we'll solve it too!

No? Reduce to zero

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Factorise binomial
Find the largest common factor and place in front of a set of single brackets, fill in the remaining factors inside the brackets.
(See §11.2). Note: the 3rd example has to be made equal to 0 first!

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Reduce to zero
Use the balance method (add/subtract the same term on both sides of the equal sign).

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Factorise trinomial
Find two numbers that have the number in front of x as a sum and the single numbers as a product. Write as (x + ...)(x + ...).
(See §11.3)

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Solving quadratic equation
4. Use the rule: if A x B = 0, then A = 0 or B =0

Next come some examples of 
Factorising Binomials and Trinomials.

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A x B = 0

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A x B = 0

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Let's do together

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Homework
Do §11.5 exercises 38, S39, 41

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