Bonjour !
1)
[tex]E=2(3x+5)(x-5)+4(x-3)\\E=2(3x^2-15x+5x-25)+4x-12\\E=2(3x^2-10x-25)+4x-12\\E=6x^2-20x-50+4x-12\\\boxed{E=6x^2-16x-62}[/tex]
[tex]F=(x+3)(x-2)-(4x+1)(2x-4)\\F=x^2-2x+3x-6-(8x^2-16x+2x-4)\\F=x^2-2x+3x-6-8x^2+16x-2x+4\\\boxed{F=-7x^2+15x-2}[/tex]
2)
[tex]K=7x\underline{(2x+3)}+10\underline{(2x+3)}\\\boxed{K=(2x+3)(7x+10)}[/tex]
[tex]L=5\underline{x^2y}-10\underline{xy^2}+15\underline{xy}\\L=xy(\underline{5}x-\underline{10}y+\underline{15})\\\boxed{L=5xy(x-2y+3)}[/tex]
Bonne journée
