d/dx xcos(x) where x= π/3?
Its another one of my practice questions for which I don't have the answer. (sorry if I'm asking loads of questions, but I want to do make sure I can do each one)
I ended up with
dy/dx= -2sin(2x)+cos(2x)
= 2.31........ where x= π/3
can you tell me if this is right or not. Thanks.
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when u do dy/dx u get -xsinx + cosx so when u replace everything with π/3 it comes out -.407
d/dx x cos(x) = x (-sin x) + cos(x) by the product rule
then plug in pi/3
-(pi/3) sin(pi/3) + cos(pi/3)
-(pi/3) (â3 /2) + 1/2
-piâ3 / 6 + 1/2
or (-3piâ3 + 3) / 6
y' = -x*sin(x) + cos(x)
y' eval. at x = pi/3: -pi/3*â3/2 + 1/2