think about which terms could be included
x^4, x^3, x^2 will all tead to terms the power of x bigger than 1
so the only bit that could be relevant is (x+1)^4
the general term in the expansion is (4n)xn where x can be 0,1,2,3,or 4
so the term you want is (41)x1=4x
so the coefficint of x is 4