Question

Calcule os cubos:
(2x+5)³

(x²-3x)³

Answer 1

= (2x + 5)³

= (2x + 5)².(2x + 5)

= (4x² + 2.5.2x + 25).(2x + 5)

= (4x² + 20x + 25).(2x + 5)

= 4x².2x + 4x².5 + 20x.2x + 20x.5 + 25.2x + 25.5

= 8x³ + 20x² + 40x² + 100x + 50x + 125

= 8x³ + 60x² + 50x + 125
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b)

= (x² - 3x)³

= (x² - 3x)² . (x² - 3x)

= ( x⁴ - 2.x².3x + 9x²).(x² - 3x)

= (x⁴ - 6x³ + 9x²).(x² - 3x)

= x⁴.x² + x⁴.(-3x) - 6x³.x² - 6x³.(-3x) + 9x².x² + 9x².(-3x)

= x⁶ - 3x⁵ - 6x⁵ + 18x⁴ + 9x⁴ - 27x³

= x⁶ - 9x⁵ + 27x⁴ - 27x³
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