1) \[(c - 6)^2 = c^2 - 12c + 36\]
2) \[(2a - 3b)^2 = 4a^2 - 12ab + 9b^2\]
3) \[(5 - a)(5 + a) = 25 - a^2\]
4) \[(7x + 10y)(10y - 7x) = 100y^2 - 49x^2\]
1) \[b^2 - 49 = (b - 7)(b + 7)\]
2) \[c^2 - 8c + 16 = (c - 4)^2\]
3) \[100 - 9x^2 = (10 - 3x)(10 + 3x)\]
4) \[4a^2 + 20ab + 25b^2 = (2a + 5b)^2\]
\[(x - 2)(x + 2) - (x - 5)^2 = x^2 - 4 - (x^2 - 10x + 25) = x^2 - 4 - x^2 + 10x - 25 = 10x - 29\]
Ответ: \[10x - 29\]
\[4(3y + 1)^2 - 27 = (4y + 9)(4y - 9) + 2(5y + 2)(2y - 7)\] \[4(9y^2 + 6y + 1) - 27 = 16y^2 - 81 + 2(10y^2 - 31y - 14)\] \[36y^2 + 24y + 4 - 27 = 16y^2 - 81 + 20y^2 - 62y - 28\] \[36y^2 + 24y - 23 = 36y^2 - 62y - 109\] \[24y + 62y = -109 + 23\] \[86y = -86\] \[y = -1\]
Ответ: \[y = -1\]
\[(4b - 9)^2 - (3b + 8)^2 = ((4b - 9) - (3b + 8))((4b - 9) + (3b + 8)) = (4b - 9 - 3b - 8)(4b - 9 + 3b + 8) = (b - 17)(7b - 1)\]
Ответ: \[(b - 17)(7b - 1)\]
\[(3 - b)(3 + b)(9 + b^2) + (4 + b^2)^2 = (9 - b^2)(9 + b^2) + (16 + 8b^2 + b^4) = 81 - b^4 + 16 + 8b^2 + b^4 = 97 + 8b^2\]
Подставим b = \(\frac{1}{2}\):
\[97 + 8 \cdot (\frac{1}{2})^2 = 97 + 8 \cdot \frac{1}{4} = 97 + 2 = 99\]
Ответ: 99
Ты молодец! У тебя всё получится!