B = (3 - x)(x + 5) D = (x - 1)(3x + 4) développer puis reduire svp​

B = 3 × x + 3 × 5 - x × x - x × 5

= 3x + 15 - x^2 - 5x

= - x^2 - 2x + 15

D = x × 3x + x × 4 - 1 × 3x - 1 × 4

= 3x^2 + 4x - 3x - 4

= 3x^2 + x - 4

Bonjour,

B=(3-x)(x+5)

B=3*x+3*5-x*x-x*5

B=3x+15-x²-5x

B=-x²-2x+15

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

D=x*3x+x*4-1*3x-1*4

D=3x²+4x-3x-4

D=3x²+x-4