Bonjour LucasBernard
[tex]3\sqrt{125}-2\sqrt{80}+\sqrt{5}=3\sqrt{25\times5}-2\sqrt{16\times5}+\sqrt{5}\\\\=3\sqrt{25}\times\sqrt{5}-2\sqrt{16}\times\sqrt{5}+\sqrt{5}\\\\=3\times5\times\sqrt{5}-2\times4\times\sqrt{5}+\sqrt{5}\\\\=15\sqrt{5}-8\sqrt{5}+\sqrt{5}\\\\=8\sqrt{5}\\\\\Longrightarrow\boxed{3\sqrt{125}-2\sqrt{80}+\sqrt{5}=8\sqrt{5}}[/tex]
[tex](3\sqrt{2}+5)^2=(3\sqrt{2})^2+2\times3\sqrt{2}\times5+5^2\\\\=3^2(\sqrt{2})^2+30\sqrt{2}+25\\\\=9\times2+30\sqrt{2}+25\\\\=18+30\sqrt{2}+25\\\\=43+30\sqrt{2}\\\\\Longrightarrow\boxed{(3\sqrt{2}+5)^2=43+30\sqrt{2}}[/tex]
[tex](\sqrt{13}+7)(\sqrt{13}-7)=(\sqrt{13})^2-7^2=13-49=-36\\\\\Longrightarrow\boxed{(\sqrt{13}+7)(\sqrt{13}-7)=-36}[/tex]
[tex]\boxed{x^2+16x+64=(x+8)^2}[/tex]
