What is a quartic function with only the two real zeros given?

x = -4 and x = -1
A. y = x^4 + 5x^3 + 5x^2 + 5x + 4
B. y = x^4 - 5x^3 - 5x^2 - 5x - 4
C. y = -x^4 + 5x^3 + 5x^2 + 5x + 4
D. y = x^4 + 5x^3 + 5x^2 + 5x - 5

Question

What is a quartic function with only the two real zeros given?

x = -4 and x = -1
  A. y = x^4 + 5x^3 + 5x^2 + 5x + 4 	
  B. y = x^4 - 5x^3 - 5x^2 - 5x - 4 	
  C. y = -x^4 + 5x^3 + 5x^2 + 5x + 4 	
  D. y = x^4 + 5x^3 + 5x^2 + 5x - 5

anonymous · Answer

b

cwrw238 · Answer

hint:    the 2 zeros are  -4  and -1  so 2 factors are (x +1) and ( x + 4)

ganeshie8 · Answer

Also by Descartes rule of signs, there should be even number of sign changes in `y` for not having any positive real zeroes

cwrw238 · Answer

the last term must be + 4

highschoolmom2010 · Answer

i dont understand how yall are getting that

ganeshie8 · Answer

you need to know `Descartes rule of signs ` and `rational root theorem`

ganeshie8 · Answer

try this https://www.youtube.com/watch?v=Jx4amKfIoP4

highschoolmom2010 · Answer

ok the decartes rule of signs kinda makes sense now

highschoolmom2010 · Answer

i dont understand the rational root theorem

highschoolmom2010 · Answer

would it be A

cwrw238 · Answer

yes