SOLUTION: What is the maximum and minimum of function y=cos4x-4cos2x+3 and its pi values

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Question 957695: What is the maximum and minimum of function y=cos4x-4cos2x+3 and its pi values
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Take the derivative and set it equal to zero,
dy%2Fdx=-4sin%284x%29%2B8sin%282x%29=0
Solutions are when x=n%2Api and x=n%2A%28pi%2F2%29
Then,
When x=n%2Api
y%5Bmin%5D=1-4%2B3=0
When x=n%2A%28pi%2F2%29
y%5Bmax%5D=1%2B4%2B3=8