028.41. a) \((a + 3)^2 - (a - 2)(a + 2)\) при \(a = -3,5\); б) \((x - 3)^2 - (x + 3)(x - 3)\) при \(x = -0,1\); в) \((m + 3)^2 - (m - 9)(m + 9)\) при \(m = -0,5\); г) \((c + 2)^2 - (c + 4)(c - 4)\) при \(c = \frac{1}{4}\).

**28.41** * **a)** \((a + 3)^2 - (a - 2)(a + 2)\) при \(a = -3.5\) \((a^2 + 6a + 9) - (a^2 - 4) = a^2 + 6a + 9 - a^2 + 4 = 6a + 13\) Подставим \(a = -3.5\): \(6(-3.5) + 13 = -21 + 13 = -8\) * **б)** \((x - 3)^2 - (x + 3)(x - 3)\) при \(x = -0.1\) \((x^2 - 6x + 9) - (x^2 - 9) = x^2 - 6x + 9 - x^2 + 9 = -6x + 18\) Подставим \(x = -0.1\): \(-6(-0.1) + 18 = 0.6 + 18 = 18.6\) * **в)** \((m + 3)^2 - (m - 9)(m + 9)\) при \(m = -0.5\) \((m^2 + 6m + 9) - (m^2 - 81) = m^2 + 6m + 9 - m^2 + 81 = 6m + 90\) Подставим \(m = -0.5\): \(6(-0.5) + 90 = -3 + 90 = 87\) * **г)** \((c + 2)^2 - (c + 4)(c - 4)\) при \(c = \frac{1}{4}\) \((c^2 + 4c + 4) - (c^2 - 16) = c^2 + 4c + 4 - c^2 + 16 = 4c + 20\) Подставим \(c = \frac{1}{4}\): \(4(\frac{1}{4}) + 20 = 1 + 20 = 21\)