Développer, réduire et ordonner : A=5+ (2x-7) (4-3x) B=3-(4x + 1)(x+2) C = 5 x - 1 + (2 x - 3) (3 x + 1) D=4x2-(-5x + 2)(x - 3) E = (2x - 3)(x + 5) - 4 (2 x - 1

Bonjour,

Pour rappel :

(a + b)(c + d) = ac + ad + bc + bd

A = 5 + (2x - 7)(4 - 3x)

A = 5 + ( 8x - 6x² - 28 + 21x )

A = 5 + 29x - 6x² - 28

A = -6x² + 29x - 23

B = 3 - (4x + 1)(x + 2)

B = 3 - (4x² + 8x + x + 2)

B = 3 - ( 4x² + 9x + 2)

B = 3 - 4x² - 9x - 2

B = -4x² - 9x + 1

C = 5x - 1 + (2x - 3)(3x + 1)

C = 5x - 1 + (6x² + 2x - 9x - 3)

C = 5x - 1 + 6x² - 7x - 3

C = 6x² - 2x - 4

D = 4x² - (-5x + 2)(x - 3)

D  = 4x² - (-5x² + 15x + 2x - 6)

D = 4x² + 5x² - 17x + 6

D = 9x² - 17x + 6

Tu essaies le dernier ? :)

Réponse :

bonjour

5+(2x-7)(4-3x)=

5+2x×4+2x×(-3x)-7×4-7×(-3x)=

5+8x-6x²-28+21x=

-6x²+29x-23

3-(4x+1)(x+2)=

3-(4x×x+4x×2+1×x+1×2)=

3-(4x²+8x+x+2)=

3-4x²-8x-x-2=

-4x²-9x+1

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

5x-1+2x×3x+2x×1+(-3)×3x+(-3)×1=

5x-1+6x²+2x-9x-3=

6x²-2x-4

4x²-(-5x+2)(x-3)=

4x²-(-5x×x+(-5x)×(-3)+2×x+2×(-3)=

4x²-(-5x²+15x+2x-6)=

4x²+5x²-15x-2x+6=

9x²-17x+6

(2x-3)(x+5)-4(2x-1)=

2x×x+2x×5+(-3)×x+(-3)×5-4×2x-4×(-1)=

2x²+10x-3x-15-8x+4=

2x²-x-11

Explications étape par étape