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

16656 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Using the product rule, differentiate: y = (x^2 - 1)(x^3 + 3).


Find the values of x such that: (log3(81)+log2(32))/(log2(x)) = log2(x) (5 marks)


A projectile is thrown from the ground at 30 degrees from the horizontal direction with an initial speed of 20m/s. What is the horizontal distance travelled before it hits the ground? Take the acceleration due to gravity as 9.8m/s^2


Solve the equation 3x^2/3 + x^1/3 − 2 = 0


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