Question

WILL GIVE BRAINLIEST TO WHOMEVER ANSWERS CORRECTLY FIRST!!!!!

Answer 1

Answer:

Step-by-step explanation:

Since this is a 4th degree polynomial, 2 of the roots will not be real.  Finding them is next to impossible off a calculator until the real ones are found first.  That's  simple enough process.

$5x^4-80=0$ and

$5x^4=80$ Divide both sides by 5:

$x^4=16$ Rewrite to get

$(x^2)^2=(2^2)^2$ which simplifies down to

$x^2=4$ Taking the square root of both sides gives you the real roots of x = 2 and -2.

That leaves you with 2 roots that are imaginary.  After you factor out the 2 and the -2 by synthetic division, you are left with the depressed quadratic

$5x^2+20=0$  Factor out the 5:

$5(x^2+4)$

So the final answer is D.