Question

efectuați:b)(x-1)(x+4)-(x-2)(×+2)
c)9(×+1)(×-1)-(3×+1)²
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Answer 1

Salut!:)

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

( x - 1 ) ( x + 4 ) = x² + 4x - x - 4 = x² + 3x - 4

( x - 2 ) ( x + 2 ) = x² - 4

x² + 3x - 4 - x² + 4 = 3x

c) 9 ( x + 1 ) ( x - 1 ) - ( 3x + 1 ) ²

( x + 1 ) ( x - 1 ) = x² - 1

(3x + 1 ) ² = 9x² + 1 + 6x

9 ( x² - 1 ) - ( 9x² + 1 + 6x )

9x² - 9 - 9x² - 1 - 6x

-10 - 6x

Bafta!:)