Question

Factorise:x²–4x-21

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Answer 1

Answer:

Step-by-step explanation:

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Answer 2

★Solution★

$x²-4x-21$

Product = -21 [-7 × 3 = 21]

Sum = -4 [-7 + 3 = -4]

Now,

$⟹x²(-7+3)x-21$

$⟹x²-7x+3x-21$

$⟹x(x-7)+3(x-7)$

$⟹(x+3)(x-7)$

Therefore, by factorising x²–4x-21, we will get = (x-3)(x-7)