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

Question 6

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

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 solve the equation by factorising, we look for two numbers that multiply to +20 (the constant term) and add to +9 (the coefficient of x). These numbers are +4 and +5.

Thus, we can write the equation as:

(x + 4)(x + 5) = 0

Step 2

Step 2: Set each factor to zero

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Answer

Next, we 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:

$x = -4$
$x = -5$

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