Posted by **thomas** on Sunday, April 7, 2013 at 8:47pm.

Please help!!

*f(x)= x(x+6)^1/2 find two x intercepts.

Then show that f'(x)=0 at some point between the 2 x intercepts.

*Use mean value theorem for f(x)= x(x^2-3x+1) for interval [1,4]

I FOUND DERIAVITIVE WHICH IS 3X^2-6X+1.THEN?

*find all critical numbers find all intervals on which the function is increasing or decreasing. lable extrma.

I FOUND MY DERIVATIVE WHICH IS -32X/(X^2-16)^2

CRITICAL NUMBERS ARE 0,4 AND -4.

SO WHAT DO i DO NEXT

- calculus -
**bobpursley**, Sunday, April 7, 2013 at 9:04pm
the two x intercepts are 0, and -6

set the derivative equal to zero, and find x

f'(x)=(x+6)^1/2 + x/2 *1/(x+6)^2=0

x+6 + x/2=0

3x=-12

x=-4

***

find f(1), and f(4)

f(1)=-1

f(4)=20

this means there is a zero between x=1,4

*****

I wonder on this third question what is the function? Putting parts of several qustion on one question is very confusing.

- calculus -
**thomas**, Sunday, April 7, 2013 at 9:19pm
f(x)=x^2/x^2-16

- calculus -
**thomas**, Tuesday, April 9, 2013 at 10:39pm
i got this. thnks

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