SOLUTION: Differentiation section of book. Find the coordinates of the stationary points on the graphs of the following function. 3x^5-20x^3+1 I tried but failed. So far I different

Question 937515: Differentiation section of book.
Find the coordinates of the stationary points on the graphs of the following function.
3x^5-20x^3+1
I tried but failed. So far I differentiated and got:
0=15x^4-60x^2+1
then I am not sure what to do. I tried to sub y=x^2:
0=15y-60y+1 but I can't factor this.
The answer given is (-2,65) (0,1) and (2,-63).
Please could someone help me?
Thanks
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Find the coordinates of the stationary points on the graphs of the following function.
3x^5-20x^3+1
I tried but failed. So far I differentiated and got:
0=15x^4-60x^2+1 ************ No 1
=====================
0=15x^4-60x^2
x^4 - 4x^2 = 0
x = 0, 0, 2, -2
Matches the answers.
then I am not sure what to do. I tried to sub y=x^2:
0=15y-60y+1 but I can't factor this.
The answer given is (-2,65) (0,1) and (2,-63).

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