Решите кто может...............................................

Question

Решите кто может...............................................

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Answer 1

Обозначим х = сх + 1 = ах + 2 = bТеорема косинусова^2 = b^2 + c^2 - 2bcCosAподставим значения(х + 1)^2 = (x+2)^2 + x^2 - (2 (x+2)x)*2/3x^2 + 2x + 1 = x^2 + 4x + 4 +x^2 - (2x^2 + 4x)*2/3x^2 + 2x + 1 - x^2 - 4x - 4 =x^2 - (2x^2 + 4x)*2/3-2x - 3 =x^2 - (2x^2 + 4x)*2/3((2x^2 + 4x)*2/3)*3 = (2x + 3 + x^2 )*34x^2 + 8x = 6x + 9 + 3x^24x^2 + 8x - 6x - 9 - 3x^2 =0x^2 + 2x - 9 =0D = 4 - 4 *1 * (-9) = 4 + 36 = 0x1 = (-2 -V40)/2 = -1 - V10 = -4.16x2 = (-2 + V40)/2 = -1 + V10 = 2.16 Выбираем x2c = x2 = 2.16a = c + 1 = 1 + 2.16 = 3.16b = a + 1 = 3.16 + 1 = 4.16

Comments

Обозначим 
х = с
х + 1 = а
х + 2 = b
Теорема косинусов
а^2 = b^2 + c^2 - 2bcCosA
подставим значения
(х + 1)^2 = (x+2)^2 + x^2 - (2 (x+2)x)*2/3
x^2 + 2x + 1 = x^2 + 4x + 4 +x^2 - (2x^2 + 4x)*2/3
x^2 + 2x + 1 - x^2 - 4x - 4 =x^2 - (2x^2 + 4x)*2/3

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-2x - 3 =x^2 - (2x^2 + 4x)*2/3
((2x^2 + 4x)*2/3)*3 = (2x + 3 + x^2 )*3
4x^2 + 8x = 6x + 9 + 3x^2
4x^2 + 8x - 6x - 9 - 3x^2 =0
x^2 + 2x - 9 =0
D = 4 - 4 *1 * (-9) = 4 + 36 = 0
x1 = (-2 -V40)/2 = -1 - V10 = -4.16
x2 = (-2 + V40)/2 = -1 + V10 = 2.16 
Выбираем x2
c = x2 = 2.16
a = c + 1 = 1 + 2.16 = 3.16
b = a + 1 = 3.16 + 1 = 4.16