find a third degree polynomial with roots 0,1 and -2

Question

johnweldon1993 · Answer

Well if we know the roots...we can make the expression

$$\large (x + 0)(x - 1)(x + 2)$$

what is this? well this is the factored version of your 3rd degree polynomial...notie how if you plug in 0...you make this expression 0

if you plug in 1...you have x - 1...which will make this whole thing = 0...and if you plug in the -2...you again get 0

so all you have to do is expand this...foil it out :)

anonymous · Answer

thank you so mcuh (:

johnweldon1993 · Answer

anytime! if you need anything else feel free to let me know :)

anonymous · Answer

i got another one ... find a third degree polynomial with roots 3 and 4-i

anonymous · Answer

do i follow the same steps? im confused on the 4-i

johnweldon1993 · Answer

Ahh no...see with complex roots it's more...complex :P

they only occur in conjugates...meaning

$$\large (x - 3)(x - (4 - i))(x - (4 + i))$$

anonymous · Answer

do i reduce this ?

anonymous · Answer

i just really suck at pre-calc :(