\( (x + 3)(x - 3) - (x - 4)^2 = x^2 - 9 - (x^2 - 8x + 16) = 8x - 25 \)
\( (5x - 1)(x + 2) + 3(x - 4)(x + 4) = 2(2x + 3)^2 - 8 \)
\( 5x^2 + 10x - x - 2 + 3(x^2 - 16) = 2(4x^2 + 12x + 9) - 8 \)
\( 5x^2 + 9x - 2 + 3x^2 - 48 = 8x^2 + 24x + 18 - 8 \)
\( 8x^2 + 9x - 50 = 8x^2 + 24x + 10 \)
\( 15x = -60 \)
\( x = -4 \)
\( (3a - 1)^2 - (a + 2)^2 = (3a - 1 - (a + 2))(3a - 1 + a + 2) = (2a - 3)(4a + 1) \)
\( (a - 6)(a + 6)(36 + a^2) - (a^2 - 18)^2 = (a^2 - 36)(36 + a^2) - (a^4 - 36a^2 + 324) = a^4 - 1296 - a^4 + 36a^2 - 324 = 36a^2 - 1620 \)
При \( a = -\frac{1}{6} \):
\( 36(-\frac{1}{6})^2 - 1620 = 36(\frac{1}{36}) - 1620 = 1 - 1620 = -1619 \)
\( (n - 6)(n - 2) - (n + 2) = n^2 - 8n + 12 - n - 2 = n^2 - 9n + 10 \)
\( (7x + 1)(x - 3) + 20(x - 1)(x + 1) = 3(3x - 2)^2 + 13 \)
\( 7x^2 - 20x - 3 + 20(x^2 - 1) = 3(9x^2 - 12x + 4) + 13 \)
\( 7x^2 - 20x - 3 + 20x^2 - 20 = 27x^2 - 36x + 12 + 13 \)
\( 27x^2 - 20x - 23 = 27x^2 - 36x + 25 \)
\( 16x = 48 \)
\( x = 3 \)
\( (2a + 1)^2 - (a - 9)^2 = (2a + 1 - (a - 9))(2a + 1 + a - 9) = (a + 10)(3a - 8) \)
\( (b - 5)(b + 5)(b^2 + 25) - (b^2 - 9)^2 = (b^2 - 25)(b^2 + 25) - (b^4 - 18b^2 + 81) = b^4 - 625 - b^4 + 18b^2 - 81 = 18b^2 - 706 \)
При \( b = -\frac{1}{3} \):
\( 18(-\frac{1}{3})^2 - 706 = 18(\frac{1}{9}) - 706 = 2 - 706 = -704 \)