Question

(7) (x-13) (x+13) =?
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Answer 1

$7 \times ( {x}^{2} - {13}^{2} ) \\ = 7 {x}^{2} - 169 \times 7 \\ \\ = 7 {x}^{2} - 1183$

Answer 2

(x-13) (x+13)

(a+b)(a-b) = a²-b²

(x-13) (x+13) = x² - 13²

= x² - 169