Let f be the function given by f(x)=2xe^(x). The graph of f is concave down when A)x<-2 B)x>-2 C)x<-1 D)x>-1 E)x<0

I know that you can use the 2nd derivative to find concavity. If f''(x) is negative, it is concave down and if its f''(x) is positive, its concave up

However, i don't know how to find f''(x) of this function

Please Help