Номер 500

1) (mn)(m + n) = m2n2;
2) (x – 1)(x + 1) = x2 – 1;
3) (9 – y)(9 + y) = 92y2 = 81 – y2;
4) (3b – 1)(3b + 1) = (3b)2 – 1 = 9b2 – 1;
5) (10m – 7)(10m + 7) = (10m)2 – 49 = 100m2 – 49;
6) (4ab)(b + 4a) = (4ab)(4a + b) = (4a)2 b2 = 16a2b2;
7) (5b + 1)(1 – 5b) = (1 + 5b)(1 – 5b) = 1 – (5b)2 = 1 – 25b2;
8) (3x – 5y)(3x + 5y) = (3x)2 – (5y)2 = 9x2 – 25y2;
9) (13c – 10d)(13c + 10d) = (13c)2 – (10d)2 = 169c2 – 100d2;
10) (8m + 11n)(11n – 8m) = (11n + 8m)(11n – 8m) = (11n)2 – (8m)2 = 121n2 – 64m2.


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