Предмет: Алгебра, автор: black9459

Помогите пожалуйста решите 128 номер

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Ответы

Автор ответа: Ляляляля109

${(x - 3)}^{2} - 8 = {x}^{2} - 6x + 9 - 8 = {x}^{2} - 6x + 1$

$12x - {(x + 6)}^{2} = 12x - ( {x}^{2} + 12x + 36) = 12x - {x}^{2} - 12x - 36 = \\ \\ = - {x }^{2} - 36$

${(2a - 3b)}^{2} - 4a(a - 6b) = 4 {a}^{2} - 12ab + 9 {b}^{2} - 4 {a}^{2} + 24ab = 12ab + 9 {b}^{2}$

${(2x - 3y)}^{2} + {(4x + 2y)}^{2} = 4 {x}^{2} - 12xy + 9 {y}^{2} + 16 {x}^{2} + 16xy + 4 {y}^{2} = \\ \\ = 20 {x}^{2} + 4xy + 13 {y}^{2}$

${(x - 5)}^{2} - x(x + 3) = {x}^{2} - 10x + 25 - {x}^{2} - 3x = - 13x + 25$

${(6a - b)}^{2} - (9a - b)(4a + 2b) = \\ \\ = 36 {a}^{2} - 12ab + {b}^{2} - (36 {a}^{2} + 14ab - 2 {b}^{2} ) = 36 {a}^{2} - 12ab + {b}^{2} - 36 {a}^{2} - 14ab + 2 {b}^{2} = \\ \\ = - 26ab + 3 {b}^{2}$

$3x {(5 + x)}^{2} - x {(3x - 6)}^{2} = 3x(25 + 10x + {x}^{2} ) - x(9 {x}^{2} - 36x + 36) = \\ \\ = 75x + 30 {x}^{2} + 3 {x}^{3} - 9 {x}^{3} + 36 {x}^{2} - 36x = - 6 {x}^{3} + 66 {x}^{2} + 39x$

${(x - 2)}^{2} + (x - 1)(x + 1) = {x}^{2} - 4 x + 4 + {x}^{2} - 1 = 2 {x}^{2} - 4x + 3$

$(3a - 2b)(3a + 2b) - {(a + 3b)}^{2} = 9 {a}^{2} - 4 {b}^{2} - ( {a}^{2} + 6ab + 9 {b}^{2} ) = \\ \\ = 9 {a}^{2} - 4 {b}^{2} - {a}^{2} - 6ab - 9 {b}^{2} = 8 {a}^{2} - 6ab - 13 {b}^{2}$