Answer:
f(-7)=21
Step-by-step explanation:
[tex]f(x)=3(x+5)^2+9\\\\f(-7)=3(-7+5)^2+9\\\\f(-7)=3(-2)^2+9\\\\f(-7)=3*4+9\\\\f(-7)=12+9\\\\f(-7)=21[/tex]