Factor completely x2 + 16.

unfactorable with real numbers

in the complex realm

(x-4i) (x+4i)

Step-by-step explanation:

x^2+16

We can only factor this with imaginary numbers

(x^2 - (-4i)^2)

This is the difference of squares

(x -4i) (x+4i)

one that is bigger than 3 1/2

step-by-step explanation:

no, her answer is not correct.   we square the lengths of all sides and then determine whether the pythagorean theorem holds here:

9² + 15² = 306.   this is not equal to the square of the longest side ( that square being 395.   answer c is correct.