Find the turning points of the curve (x^3)/3 + x^2 -8x + 5

Step one, we need to assess what the question is asking us to do, in this case, find the turning points.The turning points on the graph are where the gradient is equal to zero, so in order to find the turning points, we need to se the gradient of the graph to zero.Step 2 therefore is to find the gradient, we do this by differentiation. Remember, power down in front, one off the powerd/dx x3/3 + x2 - 8x + 5 = x2 + 2x -8Step 3 is to set the gradient we have found equal to zero and solve for xx2 + 2x -8 = 0in this case, we can factorise, what could you use if you couldn't factorise? (quadratic formula)(x - 2)(x + 4) = 0therefore, x = 2 or x = -4 have we answered the question? Not yet, we need to find the corresponding y values to our x values. Step 4, We plug our x - values back into our equationfor x = 2,y = 23/3 + 22 - 82 + 5 = -4.33for x = -4y = (-4)3/3 +(-4)2 - 8(-4) + 5 = 31.67
Finally, state the answer:turning points: (2, -4.33) and (-4, 31.67)


EM
Answered by Ellie M. Maths tutor

3419 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

Find f'(x) and f''(x) when f(x) = 3x^2 +7x - 3


How Do I Integrate cos(x) and sin(x) with higher powers?


y = 4x^3 - 5/x^2 find dy/dx


Edexcel C3 June 2015 Q1: tan(x)=p, where p is a constant. Using standard trigonometric identities, find the following in terms of p. a) tan(2x). b) cos(x). c) cot(x-45).


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