Posted by Sam on .
Can someone help me find the derivatives of these questions?
For these can you only need to tell me the answer so i can see if i have the same thing.
y=cos(4x)
y = sinx^2
y = xcosx
I need help with these 6 please.
y = xcos(1/x)
y = (1+sinx)/(1sin^(2)x)
y = sin^2x/cosx
y = sqrt(sin(sqrtx))
y = 3sqrt(xcosx)
y = 1/(sin(xsinx)

Calculus 
Reiny,
y=cos(4x)
y' = 4(sin(4x)
= 4sin(4x)
y = sinx^2 or (sinx)^2
y' = 2sinxcosx or sin 2x
y = xcosx
y' = x(sinx) + (1)cosx
= cosx  xsinx 
Calculus 
Reiny,
for y = xcos(1/x)
I would use the product rule
y' = x(sin(1/x))(1/x^2) + (1)cos(1/x)
for y = (1+sinx)/(1sin^(2)x) I would reduce it to
y = (1+sinx)/((1+sinx)(1sinx))
= 1/(1sinx)
= (1sinx)^1
now y' = 1(1sinx)^{2?sup>(cosx) why don't you show me some of the steps you have sofar for the others?} 
Calculus 
Reiny,
last line should have come out as ...
y = 1(1sinx)^{2}(cosx)