Sagot :
D=(4x-1)(4x-1) - (4x-1)(2x1)
= (4X4+4X(-1)+(-1)X4+(-1)X(-1) - (4X-1)(2X1)
= 9 - (4x-1)(2x1)
= 9- (8+4-2-1)
= 9- 9
=0
pour la a
=(4x-1)²-(4x-1)(2x+1)
= (4x-1)²-(4x*2x+4x*1-1*2x-1*1)
=(4x-1)²-(8x²+4-2x-1)
= (4x*4x+4x*(-1)-1*4x-1*(-1)-8x²-4+2x-1
=(16x²-4x-4x+2)-8x²-4+2x+1
=16x²-8x+2-8x²-4+2x+1
= 8x²+10x+3