Answer:
[tex]2x + {x}^{2} + (x + x) - 4[/tex]
when x is 3:
[tex] = 2(3) + {(3)}^{2} + (3 + 3) - 4 \\ = 6 + 9 + 6 - 4 \\ = { \boxed{ \boxed{17}}}[/tex]
Step-by-step explanation:
[tex]f(x) = 2x + {x}^{2} + (x + x) - 4 \\ f(x) = 2x + {x}^{2} +2x - 4 \\ f(x) = {x}^{2} + 4x - 4 \\ f(3) = {(3)}^{2} + 4(3) - 4 \\ f(3) = 9 + 12 - 4 \\ \boxed{f(3) = 17}[/tex]
