Question

What are the approximate values of the minimum and maximum points of

f(x) = x5 − 10x3 + 9x on [-3,3]?

Answer 1

Answer: The answers A

Explanation:

Answer 2

Find critical points by setting derivative equal to 0.

Derivative of polynomial is found by multiplying coefficient by exponent, then subtracting 1 from exponent.

f'(x) = 5x^4 - 30x^2 + 9 = 0

This is in quadratic form, use quadratic formula to find x^2


`x^2 = (15 \pm 6√(5))/(5) \\ \\ x = \pm\sqrt{(15 \pm 6√(5))/(5)} = \pm 0.5628, \pm 2.384`