developper et reduire A=2x²+5x(x-3) B=4x-2x(x-2) C=3-5x-8(2x+4) D=3+5(2x+1)

A = 2x² + 5x ( x - 3 )
= 2x^2 + 5x * x + 5x * (-3)
= 2x^2 + 5x^2 - 15x
= 7x^2 - 15x

B = 4x - 2x ( x - 2 )
= 4x - 2x * x - 2x * (-2)
= 4x - 2x^2 + 4x
= -2x^2 + 8x

C = 3 - 5x - 8 ( 2x + 4 )
= 3 - 5x - 8 * 2x - 8 * 4
= 3 - 5x - 16x - 32
= -21x - 29

D = 3 + 5 ( 2x + 1 )
= 3 + 5 * 2x + 5 * 1
= 3 + 10x + 5
= 10x + 8