Find First 3 Terms of MacLaurin Series for sec(x)

[Swatch]

I have to find the first three non-zero terms in the Maclaurin series for the function sec(x).

I guess I have to use the known Maclaurin series for cos(x) and doing 1/cos(x) series with long division. I tried that but didn't get anywere close to the right answer. Could anyone please help me?

 

[NateTG]

I have to find the first three non-zero terms in the Maclaurin series for the function sec(x).
I guess I have to use the known Maclaurin series for cos(x) and doing 1/cos(x) series with long division. I tried that but didn't get anywere close to the right answer. Could anyone please help me?

You could try checking your textbook, or googling for Maclaurin series.

 

[Swatch]

My textbook doesn't show enough exmples on this.

 

[NateTG]

How about Taylor series? (A MacLaurin series is a Taylor series about zero.)

http://mathworld.wolfram.com/MaclaurinSeries.html

 

[HallsofIvy]

My textbook doesn't show enough exmples on this.

How many examples do you need?. You may mean that your textbook has no examples of dividing by an infinite series. That's because that is much too complicated to be of any use. How about using the definition of MacLaurin series? The derivatives get a bit complicated but that's why you are only asked for the first three non-zero terms.