Разложите на множители. n^2-81 49b^2-16 81a^2-64c^2 0,04x^2-36y^2

Воспользуемся равенством:

a^2 - b^2 = (a + b) * (a - b);

1) n^2 - 81 = n^2 - 9^2 = (n + 9) * (n - 9);

2) 49 * b^2 - 16 = (7 * b) ^2 - 4^2 = (7 * b + 4) * (7 * b - 4);

3) 81 * a^2 - 64 * c^2 = (9 * a) ^2 - (8 * c) ^2 = (9 * a + 8 * c) * (9 * a - 8 * c);

4) 0.04 * x^2 - 36 * y^2 = (0.2 * x) ^2 - (6 * y) ^2 = (0.2 * x + 6 * y) * (0.2 * x - 6 * y).