Answer:
c. (-7x+4)(-7x-4)
Step-by-step explanation:
The factoring of the difference of squares is ...
a² -b² = (a +b)(a -b)
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In each of these answer choices, you have a first factor of ...
(a +b) = (-7x +4)
so, you're looking for a second factor that is ...
(a -b) = (-7x -4) . . . . . . . . matches choice C
(-7x +4)(-7x -4) results in a difference of squares
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<em>Check</em>
(-7x +4)(-7x -4) = (-7x)(-7x) +(-7x)(-4) +(4)(-7x) +(4)(-4)
= (-7x)² +28x -28x -4²
= (-7x)² -4² . . . . . . . . the difference of squares
