I really need help on how to do this derivative problem?

Question

Consider the function y = 3x5 &ndash; 25x3 + 60x + 1. Use the second derivative test to determine whether our function has a relative maximum or minimum at x = &ndash;1.

Answer

y = 3x^5 &ndash; 25x^3 + 60x + 1

y' = 15x^4 &ndash; 75x^2 + 60

y'' = 60x^3 - 150x

at x = -1

y' = 15 - 75 + 60
= 0

y'' = -60 - (-150)
= 90

ergo, it is a stationary point that is concave up
therefor it is a minimum

I really need help on how to do this derivative problem?

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