Thread: Finding critical points and equations of tangents.
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Old July 4th, 2009, 05:23 PM
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Question Finding the critical points
Quote:
Originally Posted by apcalculus View Post
2.

1.y=16x+4x^2-x^4

Differentiate
y' = 4x^3- 8x + 16 = 4 (x^3 - 2x + 4)= 4 (x+2) (x^2-2x+2)

Now solve for zeros (or critical numbers to f(x)) then study the sign to determine types of extrema.

Good luck!!
, Why is that using using quadratic formula and completing square in getting the CPs would not yield the same value such as this:
Completing Square:
0=x²-2x+2

0= x²-2x+1=-2+1
(x-1)²=-1
x-1=±√-1
x=1±√-1

Quadratic Formula:
-1±√(-2)²-4(1)(2)
(2)(1)
-1±√-4
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