Re: maths questions help
y' = 24(x+1)^2
When y'=0,
x = -1
y'' = 48(x+1)
When y''=0,
x = -1
So we can see x = -1 is both a stationary point and a point of inflexion (horizontal p.o.i.)
When x = -1, y = -1
Therefore, the stationary point of inflexion occurs at (-1,-1)