Réponse:
Bonjour
Explications étape par étape:
1) (x+5) × (x+2)
=> x×x+x×2+5×x+5×2
=> x²+2x+5x+10
=> x²+7x+10
2) (x-2) × (x+10)
=> x×x+x×10-2×x-2×10
=> x²+10x-2x-20
=> x²+8x-20
3) (2x+1) × (x+9)
=> 2x×x+2x×9+1×x+1×9
=> 2x²+18x+x+9
=> 2x²+19x+9
4) (3-x) × (5x+2)
=> 3×5x+3×2-x×5x-x×2
=> 15x+6 -5x²-2x
=> -5x²+13x+6