Which of the following best describes the roots of the polynomial function below?

Question

Which of the following best describes the roots of the polynomial function below?

A.

One real root

B.

Two real roots

C.

Two complex roots

D.

One real root and one complex root

Answer 1

Hi Juan, try sum-and-product method. If that doesn't work try quadratic formula [-b+/-sqrt(b²-4ac)]/2a.

 

Are there two numbers that add up to 5 and give you 18 when multiplied?

18*1

9*2

3*3*2

It appears there are no two such numbers.

Now you go to the quadratic formula and here is the key to using it in this case - you don't have to use the whole formula. You can just use the determinant b²-4ac and get to the answer you are looking for.   

 

5²-4*2*9=-47

That means you have complex roots, two complex roots