Question

Efetue e Simplifique.

a) x² - (x +10) ²

b) (3 x + 5) ² - 9 x²

c) (2 x - 1)² + x (3 x -2)

Answer 1

a)
= x² - (x +10) ²
= x² - [x² - 2.10x + 100]
= x² - [x² - 20x + 100]
= x² - x² + 20x - 100
= 20x - 100

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b)
= (3x + 5) ² - 9 x² 
= (3x)² + 2.5.3x + 25 - 9x²
= 9x² + 30x + 25 - 9x²

= 30x + 25

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c)
= (2x - 1)² + x.(3x - 2)
= (2x)² - 2.1.2x + 1 + 3x² - 2x
= 4x² - 4x + 1 + 3x² - 2x
= 4x² + 3x² - 4x - 2x + 1
= 7x² - 6x + 1