Answer:
a, -b
Step-by-step explanation:
When x is a, the function becomes
[tex]f(a)=3(a-a)(a+b)[/tex]
as you see, a-a is 0, and as your whole function is multiplied by this, it makes it 0.
[tex]f(-b)=3(-b-a)(-b+b)[/tex]
As you see -b+b is 0, and once again, this would make the whole function 0.
