Question

I need help with factoring a^2+81, I come up with a^2+9^2=(a+3)(a+3) but it is wrong??

Answer 1

You cannot factorise this. there is nothing like the sum of two squares!!!!!!!!

Answer 2

Thanks

Answer 3

general rule

when the discriminant of a quadratic is negative u cant factorize it.

here u have\[\Delta=0^2-4\times81<0\]

Answer 4

your question is prime because of the + sign

Answer 5

@precal: \[\text{In your first image it should be }a^2-b^2=(a+b)(a-b)\]