mintak tolong ya dibantu

(x² + 1)² - 12(x² + 1) + 20 ≤ 0
x⁴ + 2x² + 1 - 12x² - 12 + 20 ≤ 0
x⁴ - 10x² + 9 ≤ 0
(x² - 9)(x² - 1) ≤ 0
(x - 3)(x + 3)(x - 1)(x + 1) ≤ 0
buat garis bil di x = 3, x = -3, x = 1, x = -1
+ + ---- + + ----- + +
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''''-3''''-1''''''1'''''''3
hp -3 ≤ x ≤ -1 atau 1 ≤ x ≤ 3