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#1 2017-10-31 21:41:53

CIV
Member
Registered: 2014-11-09
Posts: 69

Can someone please help me with this: 2x + 4cosx = 0

I'm doing some Calculus 1 homework and I've come to a problem that I just cant figure out. I need to find where the slope of the equation below is zero.

I got the derivative without any trouble: 2x + 4cosx.

I can't figure out how to find the solution(s) though. I know that cosx = 0 at PI/2, but that isn't helping me here. I know I can factor out 2 as well, so: 2(x+2cosx) = 0.

What do I do?

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#2 2017-11-01 00:48:23

alter ego
Member
Registered: 2012-03-30
Posts: 19

Re: Can someone please help me with this: 2x + 4cosx = 0

Hi CIV,

There isn't an exact value for this so you'll have to give an approximate value.  On the MathsIsFun main site there is a function plotter.  You can plot -x as one line and 2cosx as a curve.  Zoom in to get your answer where they cross.
Alter

Last edited by alter ego (2017-11-01 00:49:30)

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