What polynomial has roots of -5, -4, and 1?

Question

anonymous · Answer

A x3 - 8x2 - 11x + 20
B x3 - x2 + 22x + 40
Cx3 + x2 - 22x - 40
D x3 + 8x2 + 11x - 20

triciaal · Answer

when you have roots  the remainder = 0 so  (x-root) is a factor 
you are given roots of -5, -4, and 1
factors are (x+5)(x+4)(x-1)
what do you get when you expand?

anonymous · Answer

Not sure D: I'm bad at this

triciaal · Answer

and you can get very good when you go slow and practice

triciaal · Answer

yes D

mrnood · Answer

You will remain 'bad at this' unless you try to become 'good at this'

start with just 2 of the brqackets and multiply them out:

(x+4)(x+1)  

(Use FOIL if you have been taight it...)

mrnood · Answer

soz @triciaal  - I'll leave this to you now!

triciaal · Answer

with practice you will see the last term is -5*-4*1 =-20 and that was the only option with -20   negative * negative * positive = negative

anonymous · Answer

I'll try :) thank you

triciaal · Answer

you are welcome anytime

anonymous · Answer

@joyraheb

anonymous · Answer

Can you help me?