Factors-9

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Express (x ² - 5x + 7) (x² + 5x - 7) as a difference of two squares.

Solution :

(x² - 5x + 7) (x² + 5x - 7)

= [x² - (5 x - 7)] [x² + (5 x - 7)]

= (x²) ² - (5x - 7)²