How do you factor $y=x^2 - 4x - 21$ ?

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Answer 1 · 2016-07-27T11:01:09

$(x-7)(x+3)$

Find factors of 21 which subtract to make 4.

Signs will be different, with more negatives.,

$7 xx3 = 21 " " 7 - 3 = 4$

$(x-7)(x+3)$

How do you factor y=x^2 - 4x - 21 y=x^2 - 4x - 21 ?