The way I did this problem was to simply graph the function |x+1| from -3 to 3. You will notice that integrating this function creates two triangles. Then use the formula for area of a triangle and add up the two separate triangles areas to get the answer. I believe its (1/2*2*2) which is the triangle from x=-3 to x=-1, and (1/2*4*4) which is the triangle from x=-1 to x=3. Adding up the two areas you get 2+8=10.