Question

(-3x+4)^2-(x+1)^2? Qual a resposta?

Answer 1

(-3x + 4)² - (x + 1)²

(-3x + 4)(-3x + 4) - [(x + 1)(x + 1)]
9x² - 12x - 12x + 16 - [(x² + x + x + 1)]
9x² - 24x + 16 - [(x² + 2x + 1)]
9x² - 24x + 16 - x² - 2x - 1
9x² - x² - 24x - 2x + 16 - 1
8x² - 26x + 15

Delta = b² - 4ac
Delta = (-26)² - 4(8)(15)
Delta = 676 - 480
Delta = 196

X = (-b +- raiz delta) / 2a
X = (26 +- 14) / 16
x' = (26 + 14) / 16 = 40/16 = 5/2
x" = (26 - 14) / 16 = 12/16 = 3/4

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