Développer et réduire chaque expression: a) (x+1)(x+2) b) (x+2)(x+5) c) (5+x)(x+1) d) (x+2)(3+x)

Bonsoir,

a) (x+1)(x+2)
= x² + 2x + x + 2
= x² + 3x + 2

b) (x+2)(x+5)
= x² + 5x + 2x + 10
= x² - 7x + 10

c) (5+x)(x+1)
= 5x + 5 + x² + x
= x² + x + 5x + 5
= x² + 6x + 5

d) (x+2)(3+x)
= 3x + x² + 6 + 2x
= x² + 3x + 2x + 6
= x² + 5x + 6