Question

Can anyone tell me why x^2 − 8x − 11 is prime? I know it is prime, I just don't know how to explain why it is.

Answer 1

\[x ^2 - 8 - 11\]

Answer 2

is the trinomial

Answer 3

a number is prime if it can only be divide by 1 and itself, right?

Answer 4

yes

Answer 5

so if one part in the equation is prime the equation itself is prime?

Answer 6

I guess this equation has no whole number factors

Answer 7

or solutions*

Answer 8

im confused now :?

Answer 9

ok what are the solutions of \(x^2-16=0\)

Answer 10

(x+4) (x-4)

Answer 11

you can't factor it like that because you can't write -8 in terms of the factors of 11, you'd have to complete the square

Answer 12

\(x^2 − 8x − 11=(x-4)^2-27\)

Answer 13

Then how do i make x2 − 8x − 11 a prime equation?

Answer 14

its asking to find a prime trinomial and explain why it is prime. I went to another site and the said it was prime so i came here. So i need a new trinomial...

Answer 15

it is prime

Answer 16

http://www.saylor.org/site/wp-content/uploads/2013/02/RWM102-9.3.4-Prime-Trinomials-FINAL.pdf
remember what I said about the factors of 11?

Answer 17

yes

Answer 18

only 11 and 1 because it is prime

Answer 19

\(x^2-8x-11\)
we want factors of -11 that add/subtract up to -8

Listing the factors of -11:
-1 x 11= -11

none (well in this case we only have one) of these add up to -8 so this can't be factored

Answer 20

that makes sense now

Answer 21

thank you (:

Answer 22

anytime c: