Question

помогите решить
$16x ^{2} < 81$
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Answer 1

$16 {x}^{2} - 81 < 0 \\ (4x - 9)(4x + 9) < 0 \\ (4x - 9)(4x + 9) = 0 \\ 1) \ 4x - 9 = 0 \\ x = \frac{9}{4} = 2.25 \\ \\ 2) \: 4x + 9 = 0 \\ \\ x = - \frac{9}{4} = - 2.25 \\ \\ + + + ( - 2.25) - - - (2.25) + + + >_x \\ \\ OTBET: \: x \in ( - 2.25; \:2.25)$