umm.. ther are both seperate questions.. i do understand what the graph looks like.. but the working out it tricky..
sum 1.
f(x) = x^5
f'(x) = 5x^4 when f'(x)=0, x=0 and y=0.
then f''(x) = 20x^4 so when f''(x) = 0, x=0 hence it can be a point of horizontal inflexion. but when we check for...