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1calculus1
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Homework Statement
Find all critical numbers of f(x)= x[tex]\sqrt{2x+1}[/tex]
Homework Equations
Derivative, Product Rule
The Attempt at a Solution
x[tex]\sqrt{2x+1}[/tex] = 0
x must be -1/2 & 0
(-1/2, 0) Critical Point.
(0, 0) Critical Point.
First derivative:
f'g + g'f
(1)([tex]\sqrt{2x+1}[/tex])+(1/2[tex]\sqrt{2x+1}[/tex])(x)(2)
=([tex]\sqrt{2x+1}[/tex]) + (x / [tex]\sqrt{2x+1}[/tex])
LCD:
(([tex]\sqrt{2x+1}[/tex]) ([tex]\sqrt{2x+1}[/tex]) + 1)) / ([tex]\sqrt{2x+1}[/tex])
= 2x+1 / [tex]\sqrt{2x+1}[/tex]
So y= 0 when x= -1/2 and 0
(-1/2, 0) Critical Point.
The second derivative I wouldn't post it her since it gets pretty messy. However, I found out that y=o for the second derivative must have x = -1/2
Now the problem is that my answer for all critical points are wrong. What am I doing wrong? PPLEASE HELP!