Find all positive values for k for which each of the following can be factored.

x^2+3x+kthe coefficent of the middle term is 3
3=2+1
k=2*1=2

did i do this right

This one I had no Idea where to start can some one please explain it to me
x^2+x-k

The second one cannot be factored with real numbers, the factors will be complex (real and imaginary).

The first is right, if you mean..
x^2+3x+k= (x+2)(x+1)
I am not certain of what you are doing. There are many more values of k what will work to get factors, in fact, and infinite number..
x^2+3x + 9/4 = (x+3/2)(x+ 3/2) and so on.