first, look at kerv...(x+1)*(x+4)=o...or x^2 +5x+4=0
=parabola that go thru points: (-1,0) & (-4,0)
hav x^2, so yuno it go up (vertikal axis)
<0 impli yu want area belo parabola
dy/dx=2x+5=slope & slope=0 at 2x=-5...or x=-2.5...thats bottom av parabola