# AS Gradient Functions Question HELP!!Watch

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#1
^^See attached image. I have done part (i) but I don’t understand what (ii) is asking me to do. Any ideas?
0
1 week ago
#2
(Original post by Reena Bansi)
^^See attached image. I have done part (i) but I don’t understand what (ii) is asking me to do. Any ideas?
Seems self explanatory. Differentiate y to get dy/dx. Sketch dy/dx like any other function of x, and compare it with what you got for part (i).
0
1 week ago
#3
(Original post by Reena Bansi)
...
i) Intuitively sketch f'(x) by thinking about the grad of f(x) i.e) for each portion of the graph, is grad +ve or -ve, increasing or decreasing? You know f'(x) = 0 at x = 1, 5 from the turning points of f(x).

ii) Differentiate to get a quadratic, did you sketch this initially in i)? Solve it, you should get 1, 5 as the roots, agreeing with the sketch in i).
1
1 week ago
#4
(Original post by Reena Bansi)
^^See attached image. I have done part (i) but I don’t understand what (ii) is asking me to do. Any ideas?
As above. The whole "comparing" part is checking whether your f'(x) is +ve whenever f(x) is increasing, whether f'(x) is zero when f(x) reaches its stationary points, and whether f'(x) is negative whenever f(x) is decreasing. These things have to agree.
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