Using a2 − b2 = (a + b) (a − b), find 12.12 − 7.92

12.12 − 7.92 = (12.1 + 7.9) (12.1 − 7.9) = (20.0) (4.2) = 84

Using Asquare2 − Bsquare2 = (A + B) (A − B), Find 12.1square2 − 7.9square2

Using a²− b² = (a + b) (a − b), find 12.1² − 7.9²

12.1² − 7.9² = (12.1 + 7.9) (12.1 − 7.9)

= (20.0) (4.2) = 84

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