Question

x(7x+2)-(x+1)² при x=
$\sqrt{12}$

Answer 1

X(7x+2)-(x+1)²=7х²+2х-х²-2х-1=6х²-1=6(√12)²-1=72-1=71

Answer 2

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Решение:
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$x(7x + 2) - (x + 1)^{2} = 7 {x}^{2} + 2x - {x}^{2} - 2x - 1 = \\ = 6 {x}^{2} -1$
Если х = √12, то
$6 {x}^{2} - 1 = 6( \sqrt{12} {)}^{2} - 1 = \\ = 6 \times 12 -1 = 72 - 1 = 71$

Ответ: 71