Réponse:
1) E=(x-3)(5x+2)-(x-3)²
=5x²+2x-15x-6-(x²-2×x×3+3²)
=5x²-13x-6-x²+6x-9
=4x²-7x-15
2) E=(x-3)(5x+2)-(x-3)²
=(x-3)(5x+2-(x-3))
=(x-3)(5x+2-x+3)
3) E=(x-3)(4x+5)=0
x-3=0 ou 4x+5=0
x=3. ou 4x=-5
x=3. ou. x= -5/4
