Calc please help with question 32 part b?

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1 Answer
Jim H
Nov 19, 2017

It looks like you've made an algebra error.

Explanation:

#2x(900+32x-x^2)# should be #-2x^3+64x^2+1800x#

Now when you differentiate you'll get

#R'(x) = -6x^2+128x+1800#

and #R'(14) = -6(14^2) + 128(14)+1800 = 2416#

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