Verified answer

Bonjour,

Développer les expressions suivantes  :

a. ( 2x+1)(3-x)

= 6x - 2x² + 3 - x

= - 2x² + 6x - x + 3

= - 2x² + 5x + 3

b. (5-2x)(3-x)-3(3-2x)  

= 15 - 5x - 6x + 2x² - 9 + 6x

= 2x² - 5x - 6x + 6x + 15 - 9

= 2x² - 5x + 6

c.(x+1)²+(2x-1)²

C = x² + 2x + 1 + 4x² - 4x + 1

C = x² + 4x² + 2x - 4x + 1 + 1

C = 5x² - 2x + 2

d.(x-2)(2x-1)(5-x)

= (2x² - x - 4x + 2) (5 - x)

= 10x² - 2x³ - 5x + x² - 20x + 16x² + 10 - 2x

= - 2x³ + 10x² + x² + 16x² - 5x - 20x - 2x + 10

= 2x³ + 27x² - 27x + 10.