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

15965 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

(A-Level) Find the coordinate of the stationary point of the curve y = 2x + 27/x^2


A curve has equation y=x^2 + (3k - 4)x + 13 and a line has equation y = 2x + k, where k is constant. Show that the x-coordinate of any point of intersection of the line and curve satisfies the equation: x^2 + 3(k - 2)x + 13 - k = 0


How do you solve an equation by completing the square?


Differentiate y = x^3 + 2x^2 + 4x + 3


We're here to help

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

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences