Question

Simplifique as expressões abaixo:
a) [x+ 7]² - [x - 7]²=

b) [x + 1]² - [x - 2]²=

c) [x + 5]² - [x - 5]²=
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Answer 1

Resposta:

a) (x + 7)² - (x - 7)² = 28x

b) (x + 1)² - (x - 2)² = 6x -3

c) (x + 5)² - (x - 5)² = 20x

Explicação passo a passo:

a) (x + 7)² - (x - 7)² = [(x + 7) + (x - 7)].[(x + 7) - (x - 7)] =

= [x + 7 + x - 7].[x + 7 - x + 7] =

= [2x].[14] =

= 28x

b) (x + 1)² - (x - 2)² = (x² + 2x + 1) - (x² - 4x + 4) =

= x² + 2x + 1 - x² + 4x - 4 =

= 6x -3

c) (x + 5)² - (x - 5)² = [(x + 5) + (x - 5)].[(x + 5) - (x - 5)] =

= [x + 5 + x - 5].[x + 5 - x + 5] =

= [2x].[10] =

= 20x