Question

The function f(x)=2x^3+x-5 has one real zero. It is between what?

Please explain how to get the answer.

Answer 1

if f(a) is -

and f(b) is +

it would have to cross since its a poly; and polys are continuous

Answer 2

cubics by nature have at least 1 crossing

Answer 3

It's multiple choice and I have these answers:

-2 and -1
-1 and 0
0 and 1
1 and 2
2 and 3

I'm still confused on which is the right the answer.

Answer 4

I'm assuming if you want what its between there are no integer roots.
Plug in 1 you get:-2 then when you plug in 2 you get:13 Since it went from - to + that means its between 1 and 2.

Answer 5

plug and chug .... trial and error

Answer 6

Ahhhh I understand. Thank you so much.