Question

find the polynomial function with roots 1, -2, and 5

Answer 1

when you have a root of -2 it is written as (x+2) saying that when x=-2 then (x+2) is zero.

So root of 1 would be written as (x+1)

let say now that you have a function with roots of

3,4,-5 then you would write it as
f(x)=(x-3)(x-4)(x+5)

can you do your problem now, or still need more help ?

Answer 2

So it would be f(x)=(x-1)(x+2)(x-5) ?

Answer 3

yes, you are correct. I am not sure if you have to expand it or not, but I normally would.