Identify the factors of x2 − 4x − 21. (x − 7)(x + 3) (x + 7)(x − 3) (x + 21)(x − 1) (x − 21)(x + 1)

asked Oct 15, 2018 129k views

2 votes

Identify the factors of x2 − 4x − 21.

(x − 7)(x + 3)
(x + 7)(x − 3)
(x + 21)(x − 1)
(x − 21)(x + 1)

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1 vote

Answer: the answer is A

Explanation:

(x-7)(x+3)

FredLoh answered Oct 16, 2018

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6 votes

x^2-(7-3)x-21=0
=>x^2-7x+3x-21=0
=>x(x-7)+3(x-7)=0
=>(x+3)(x-7)=0

therefore, (x-7)(x+3) is the correct answer.

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