Bonsoir,

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

A(x) = 2x*x + 2x*4 - x - 4 + 2x - 1

A(x) = 2x² + 8x - x - 4 + 2x - 1

A(x) = 2x² + 9x - 5

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

A(x) = (2x - 1)(x + 4) + (2x - 1) * 1   je peux factoriser par (2x-1)

A(x) =  (2x - 1) * (x + 4 + 1)

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

Bonne soirée