[tex]\longrightarrow{\blue{f(-3)\:=\:3}}[/tex]
[tex]\large\mathfrak{{\pmb{\underline{\red{Step-by-step\:explanation}}{\red{:}}}}}[/tex]
[tex]f(x) = {x}^{2} + 2x[/tex]
For [tex]f( - 3)[/tex], substitute "[tex]-3[/tex]" for each occurrence of "[tex]x[/tex]".
[tex]f( - 3) = ( { - 3})^{2} + 2( - 3)[/tex]
[tex] = ( - 3 \times - 3) - 6[/tex]
[tex] = 9 - 6[/tex]
[tex] = 3[/tex]
[tex]\large\mathfrak{{\pmb{\underline{\orange{Mystique35 }}{\orange{❦}}}}}[/tex]