Why cant x^2+81 be factored?

Question

anonymous · Answer

with real numbers, several reasons
one is that $$x^2+81\geq 81$$  so it is never zero
if you could factor it, it would have zeros

anonymous · Answer

not sure what "reason" means in this context, but you can always factor the DIFFERRENCE of two squares, but not the SUM

anonymous · Answer

of two square

anonymous · Answer

what do you mean by difference of two squares but not the sum

anonymous · Answer

Just simply use the quadratic equation

kl0723 · Answer

example (x^2-4) and (X^2+4) difference and sum

anonymous · Answer

@satellite73  are you saying you can only factor it if its a minus sign and not adding sign?

kl0723 · Answer

is the example given to you was (x^2-81) it could be factored because is a difference of squares but not (x^2+81) since is a sum :)

anonymous · Answer

ohhhhhhhhhhhhhhhhhhhhhhhhhhhhhh that makes a lot of sense not but what would it be if it was x^2-81?

anonymous · Answer

(x+9) (x-9)?

kl0723 · Answer

(x+9)(x-9) = x^2-9x+9x-81... 9x-9x =0 and cancel leaving you with x^2-81 :)

anonymous · Answer

thanks that helps a lot!