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Solve by factorising - OCR - GCSE Maths - Question 6 - 2019 - Paper 1

Question 6

Solve by factorising. $$x^2 + 9x + 20 = 0$$

Worked Solution & Example Answer:Solve by factorising - OCR - GCSE Maths - Question 6 - 2019 - Paper 1

Step 1

Step 1: Factor the quadratic equation

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Answer

To factor the equation $x^2 + 9x + 20$ , we need to find two numbers that multiply to +20 (the constant) and add to +9 (the coefficient of the linear term). These two numbers are +4 and +5. Thus, we can rewrite the equation as:
$(x + 4)(x + 5) = 0$

Step 2

Step 2: Set each factor to zero

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Answer

Now, we can set each factor equal to zero:

$x + 4 = 0$
$x + 5 = 0$

Step 3

Step 3: Solve for x

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Answer

Solving these equations gives us:

$x = -4$
$x = -5$
Therefore, the solutions are $x = -4$ or $x = -5$ .

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