Write the polynomial in standard form and identify the zeros of the function and the x-intercepts of its graph.

1)f(x)=(x-3i)(x+3i)

Question

Write the polynomial in standard form and identify the zeros of the function and the x-intercepts of its graph. 

1)f(x)=(x-3i)(x+3i)

anonymous · Answer

polynomial will be $$x ^{2}+9$$

anonymous · Answer

Do I use foil?

anonymous · Answer

roots are complex and $$(x + y)( x - y) = ( x ^{2} - y ^{2})$$ and square of i is -1

anonymous · Answer

Okay, that makes sense.. and how do I figure out what the zeros would be?

anonymous · Answer

you are looking at them

anonymous · Answer

+or-3i?

anonymous · Answer

you have it in factored form, so you know the zeros. just like if i have $(x-1)(x+2)$ i know the zeros are 1 and -2

yes what you said

anonymous · Answer

Okay, and what about x-intercepts? How do I find those?

anonymous · Answer

the zeros are complex, so there are none

anonymous · Answer

yeah zeroes are + 3i and -3i. Polynomial is in factored form. X -intercepts will be zero as they have only complex values

anonymous · Answer

Okay. What if they weren't complex? How would I find them?

anonymous · Answer

$$y=x^2+9$$ sits entirely above the $x$ axis |dw:1348842360330:dw|

anonymous · Answer

set the quadratic equal to zero and solve
factor
complete the square
use the quadratic formula
whatever you can do

anonymous · Answer

Ohh, okay! Thanks