D (f) y=корень из 9 х^2-4

√ (18X^2 - 9) = X^2 - 4

(√ 18X^2 - 9) = (X^2 - 4) ^2

18X^2 - 9 = X^4 - 8X^2 + 16

X^4 - 8X^2 - 18X^2 + 16 + 9 = 0

X^4 - 26X^2 + 25 = 0

X^2 = A; A > 0

A^2 - 26A + 25 = 0

D = 676 - 100 = 576; √ D = 24

A1 = (26 + 24) : 2 = 25; > 0

A2 = (26 - 24) : 2 = 1; > 0

X^2 = 25

X = 5; X = - 5

X^2 = 1

X = 1; X = - 1

Ответ 5; - 5; 1; - 1