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Zadanie 27. (2 pkl)

Rozwiąż równanie .r³ - 6.r² - 12.r + 72 = 0.

c

x³ - 6x² - 12* + 72 = 0 (x³ - 6x²) + (—12x + 72) = 0 x²(x — 6) — 12(x — 6) =0

(x² - 12)(x- 6) = 0 (x - vl2)(x + \12)(x - 6) = 0 (x - \ 4 ■ 3)(x + \ 4 • 3)(x - 6) = 0 (x - 2\/3)(x + 2\/3)(x - 6) = 0

x — 2\f3 = 0 U x + 2\f3 = 0 U x — 6 = 0 x = 2\l3    x=-2\f3    x = 6

x³-6x²-12x + 72 = 0 < = >xe{-2V3,2V3,6}