theres a calculator yoy can buy, it makes it a lot easier: Texas Instruments TI-84 Plus. its a bit big but it works well.
Answer:
-1, 3, -3
Step-by-step explanation:
I don't see the graph, but you can solve by factoring:
By the factor theorem, the solutions of f(x) are -1, 3, and -3.
Where's the question??
1and2and3and4and5and5