Question 864867
F(x)= 3-(8+7x)^2/7 
Derivative: 
(from the example problem, figured it out, but don't really know how the 7 cancels out)
F'(x)=-2/7(8+7x)^-5/7
F'(x)=-2(8+7x)^-5/7 Derivative. 
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The 7's cancel because d/dx of (8+7x) is 7.
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f'(x) = 0
-2(8+7x)^-5/7 = 0
(8+7x)^-5/7 = 0
8+7x = 0
x = -8/7
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The point (-8/7,3) is a cusp, there is no max or min of the function.