Question

Calc. question clarification / progress check help please?

Answer 1

The function h is given by h(x)=cos(kx)[f(x)]+sin(x) for all real numbers, where k is a constant. Find h ′(x) and write an equation for the line tangent to the graph of h at x=0.

My question is this: No constant for k is given, and I don't think I can find a proper tangent equation without one, so do I make up one?

Answer 2

My progress thus far has been to make h(x) = (g(x)*f(x)) + sin x, where g(x) = cos kx and use the product rule to get h(x) = (g'*f + f'+g) + sin x. Is this correct so far?

Answer 3

OOPS

Answer 4

I mean h'(x) = (f'g+g'f) + cos x

when h(x) = g(x)*f(x) + sin x

Answer 5

Is *that* right so far?

Answer 6

Oh! Since k is a constant and x = 0, k doesn't really matter anyways, does it?

Answer 7

@ganeshie8 @zepdrix @

Answer 8

I know it's rude to barge in on other people's questions, but can someone PLEASE help?

http://openstudy.com/study#/updates/568870cae4b032ed60df4720

Answer 9

I'll look at it in a sec, nhs

Answer 10

ya your progress looks good so far,
you get something like this for your derivative, right?\[\large\rm h=(\cos kx)f+\sin x\]\[\large\rm h'=(-\sin kx)f+(\cos kx)f'+\cos x\]

Answer 11

And then, yes, since k is constant, constant*0 = 0.
So not knowing your k won't be a problem :)

Answer 12

That looks right. Anyways thanks! I think all of my issues have cleared up.

Answer 13

Woops, my derivative was wrong,
should have a k coefficient in front of the sinkx, my bad.

Doesn't affect anything though, yay team

Answer 14

Yeah I had it on wolfram, no worries.

Answer 15

that is just h'. You need h'(0) and put it into the equation of tangent line.

Answer 16

Right. I understood that, I just wanted to check my progress and understanding of the question. Thanks though