Need Help Solving nth Derivative of e^ax*Sin(ax+b)

  • Thread starter Tanny Nusrat
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In summary, the conversation is discussing the nth derivative of a function. The solution involves using the product rule and results in a cyclic pattern that can be written down as a set of four cases. The person asking for confirmation has provided their solution and is waiting for someone to confirm it. They are also advised to use latex to properly display their formulas. There is a discrepancy in the original function and the formula for the nth derivative, so it is suggested to check for any misreadings.
  • #1
Tanny Nusrat
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i have solved the following one but not sure...anyone give me the solve..i want to be sure..

nth derivative of {e^ax * Sin(ax+b)}
 
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  • #2
Show your solution and your working, as requested in the sub-forum guidelines, and I'm sure somebody will confirm it, or correct it if wrong.

You need to use the product rule. Once you've differentiated several times you'll see a cyclic pattern that can be written down as a set of four cases.
 
  • #3
ok..here is my solution...somebody please confirm me..

b^n * e^ax * Sin {(n*pi/2)+(bx+c)} + n*a*b* e^ax * Sin {pi/2+(bx+c)} + a^n * e^ax * Sin (b+c)
 
  • #4
Substitute n=1 into your formula and then compare to what you get when you differentiate once, ie ##\frac{d}{dx}\big(e^{ax}\sin(ax+b)\big)##.

Do they look the same?

Post the working by which you arrived at your conclusion and somebody can show where you went wrong. Did you try what I suggested in post 2?

If you use latex to properly display your formulas you will also improve your chances of getting help. The latex tutorial is here.
 
  • #5
Your original function has "ax+ b" while your formula for the nth derivative has "bx+ c". Was one of those a misreading?
 

1. What is the formula for finding the nth derivative of e^ax*Sin(ax+b)?

The formula for finding the nth derivative of e^ax*Sin(ax+b) is:

d^n/dx^n (e^ax*Sin(ax+b)) = a^n*e^ax*Sin(ax+b) + a^(n-1)*cos(ax+b) + a^(n-2)*(-1)^2*sin(ax+b) + ... + a*(-1)^(n-1)*cos(ax+b) + (-1)^n*sin(ax+b)

2. How do I solve for the nth derivative of e^ax*Sin(ax+b)?

To solve for the nth derivative of e^ax*Sin(ax+b), you will need to use the formula mentioned in the previous answer. Plug in the value of n and simplify the expression to get the final result.

3. Can I use the chain rule to find the nth derivative of e^ax*Sin(ax+b)?

Yes, you can use the chain rule to find the nth derivative of e^ax*Sin(ax+b). The chain rule states that the derivative of the composition of two functions is equal to the derivative of the outer function evaluated at the inner function, multiplied by the derivative of the inner function. In this case, the outer function is e^ax and the inner function is Sin(ax+b).

4. How does the value of a and b affect the nth derivative of e^ax*Sin(ax+b)?

The values of a and b affect the nth derivative of e^ax*Sin(ax+b) by determining the coefficients of the terms in the final expression. The value of a affects the coefficients of e^ax and cos(ax+b) terms, while the value of b affects the coefficients of Sin(ax+b) and cos(ax+b) terms.

5. Is there a shortcut or simpler method to find the nth derivative of e^ax*Sin(ax+b)?

No, there is no shortcut or simpler method to find the nth derivative of e^ax*Sin(ax+b). You will need to use the formula and simplify the expression to get the final result. However, you can use a calculator or computer program to evaluate the expression for a specific value of n, a, and b.

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