Factor x2 plus 2x plus 4?

Answer 1

x2 + 2x + 4 can be expressed in the form ax2 + bx + c, where a=1, b=2, c=4.

So you will be looking for two numbers that add to 2 [b], and multiply to 4 [ac]. Clearly, there are no two real numbers that can do this. Therefore the expression above cannot be factorised.