Help with Maclaurin series question

[jayz]

I'm having trouble with this series. I cant find the values for c4 and c6. I have tried to take the derivative to those points but what I found was that the x carries out and since the x is zero, wouldn't that make the answer 0? the derivative for c4 I got was 9(14x)^4cos(7x^2)

 

[Ishuda]

I'm having trouble with this series. I cant find the values for c4 and c6. I have tried to take the derivative to those points but what I found was that the x carries out and since the x is zero, wouldn't that make the answer 0? the derivative for c4 I got was 9(14x)^4cos(7x^2)

That looks like part of f'''. The derivatives turn into a long mess but you just have to keep after it. What do you have for the derivatives so far?