Find the stationary points on the curve y = x^3 + 3x^2 - 9x - 4

A stationary point is where the gradient is exactly zero - the curve is neither increasing or decreasing. This means that we need to differentiate y to find dy/dx and then set this equal to 0. Doing this, using the normal rules for differentiation, we would get 3x^2 + 6x -9 Then, we would set this equal to zero and factorise the equation to find out the x values of our stationary points. Doing this, we get (x + 3)(x - 1) = 0 Leaving x=-3 or x=1 Finally, substitute these values into y = x^3 + 3x^2 -9x -4 and this will give you the y-coordinates to the stationary points. The final answers are therefore (-3,23) and (1,-9)

RR
Answered by Richard R. Maths tutor

16661 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

A curve has an equation: (2x^2)*y +2x + 4y – cos(pi*y) = 17. Find dy/dx


Integrate 3t^2 + 7t with respect to t, between 1 and three.


A curve has the equation x^2 +2x(y)^2 + y =4 . Find the expression dy/dx in terms of x and y [6]


Using the Quotient rule, Find dy/dx given that y = sec(x)


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning