Maths Help (1 Viewer)

[ozidolroks]

For the 2005 HSC Maths paper, Question 10 iv) I don't understand how they differentiated in the solutions. Can you please explain it to me? I tried using the product rule but it doesn't turn out to be the same answer.

Thanks

 

[boxhunter91]

they are respecting x. If you look at the solutions mx-->m and x^2 becomes 2x..

 

[cutemouse]

What's the question?

 

[kelllly]

they are respecting x. If you look at the solutions mx-->m and x^2 becomes 2x..

Area = 1/2 (mx - x^2 + b) (m^2 + 4b)^(1/2)

[Underlined = Constants]

Rearranging that:

Area = 1/2 (m^2 + 4b)^(1/2) (mx - x^2 + b)

d(Area)/dx = 1/2 (m^2 + 4b)^(1/2) (m - 2x)