Resposta :
[tex](10+3x)(10-3x)=10^2-(3x)^2=100-9x^2[/tex]
[tex](10+3x)(10-3x)=100-\not30x+\not30x-9x^2=\boxed{100-9x^2}[/tex]
[tex](10+3x)(10-3x)=100-\not30x+\not30x-9x^2=\boxed{100-9x^2}[/tex]