1a)
(2x-3)(5x+2)
= 2x × 5x + 2x×2 -3×5x +(-3)×2
=10x²+4x-15x-6
=10x²-11x-6
1b)
(8x-8)(2x-3)
=8x×2x + 8x×-3 -8×2x -8×-3
=16x²-24x -16x+24
=16x²-40x+24
2a)
(10x²-11x-6)-(16x²-40x+24)
=10x²-11x-6 -16x² +40x-24
=10x²-16x² -11x+40x -6-24
=-6x²+29-30
3)
(2x-3)(5x+2)-(8x-8)(2x-3)
Il faut mettre le 2x-3 en facteur
(2x-3)(5x+2-8x+8)
=(2x-3)(-3x+10)
4) On remplace x par -1
A=(2×-1-3)(-3×-1+10)
A=(-2-3)(3+10)
A=(-5)×(13)
A=-65