Bonsoir,
• (3x+1)(3x-1)-6x(x+3)²
= 9x² -3x +3x -1 -6x( x² +6x +9)
= 9x² -3x +3x -1 -6x³-36x² -54x
= -6x³ -27x² -54x -1
• -9(7x+9)(5x-8)-(8x-9)²
= (63x +81) ( 5x-8) -( 64x² -144x +81)
= 180x² -504x 405x -648 -64x²+144x -81
= je te laisse compter
• -10(3x-5)(7-11x)-3(8x+9)²
(-30x +50)( 7-11x) -3(64x² +144x +81)
= -210x +330 +350 - 550x - 192x² - 432x - 243
= je te laisse compter
