Question

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

x = -4 and x = -1

Answer 1

A. y = x4 + 5x3 + 5x2 + 5x + 4

B. y = x4 - 5x3 - 5x2 - 5x - 4

C. y = -x4 + 5x3 + 5x2 + 5x + 4

D. y = x4 + 5x3 + 5x2 + 5x - 5

Answer 2

@jim_thompson5910 can you help me with this

Answer 3

quartics are ugly (esp with factoring/solving), so the best thing to do is plug in each possible root into each answer choice

Answer 4

and see which equation gives you a result of zero for each root

Answer 5

so check choice A

y = x^4 + 5x^3 + 5x^2 + 5x + 4

y = (-4)^4 + 5(-4)^3 + 5(-4)^2 + 5(-4) + 4 ... plug in x = -4

y = 256 + 5(-64) + 5(16) + 5(-4) + 4

y = 256 - 320 + 80 - 20 + 4

y = 0

So x = -4 is a root to y = x^4 + 5x^3 + 5x^2 + 5x + 4 since we get a result of 0

Do the same for x = -1 and see if it is a root or not

Answer 6

oh thanks so much :) @jim_thompson5910

Answer 7

yw