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Sagot :

AENEAS

Bonsoir,

On a :

A = 7x(x+2) + (2x-1)(3x-5)

A = 7x² + 14x + (6x² - 10x - 3x + 5)

A = 7x² + 14x + 6x² - 13x + 5

A = 13x² + x + 5

B = (7x+3)²

B = 49x² + 42x + 9

C = (4x-1)(4x+1) - (x-5)²

C = (16x² - 1) - (x² - 10x + 25)

C = 16x² - 1 - x² + 10x - 25

C = 15x² + 10x - 26

Réponse:

A= 7x(x+2)+(2x-1)(3x-5)

=( 7x²+ 14x)+ (6x²-10x-3x+5)

=7x²+14x+6x²-13x+5

= 7x²+6x²+14x-13x+5

= 13x²+x+5

B= (7x+3)²

identité remarquable

(a+b)²= a²+2ab+b²

= (7x)²+2× 7x × 3+ 3²

= 49x²+ 42x+9

C= (4x-1)(4x+1)-(x-5)²

identité remarquable (a+b)(a-b)= a²-b²

et

(a-b)²= a²-2ab+b²

= 16x²-1-(x²-2×x×5+5²)

=16x²-1-(x²-10x+25)

= 16x²-1-x²+10x-25

=15x²+10x-26

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