bonsoir,
A. x(2x - 1) - (3x + 1)
= 2 x² - x - 3 x - 1
= - 2 x² - 4 x - 1
B. (2x + 1)² + 3(x - 5)
= 4 x² + 4 x + 1 + 3 x - 15
= 4 x² + 7 x - 14
C.(2x - 1)(2x + 1) - 4x(x - 1)
= 4 x² - 1 - 4 x² + 4
= 3
D.-2(5 + 2x)² – (3x + 4)(x - 2)
= - 2 ( 25 + 20 x + 4 x² ) - ( 3 x² - 6 x + 4 x - 8 )
= - 50 - 40 x - 8 x² - 3 x² + 6 x - 4 x + 8
= - 11 x² - 38 x - 42
( x + 5 ) ( x - 3 ) + 15
= x² - 3 x + 5 x - 15 + 15
= x² + 2 x
donc multiple de x
