- #1
MissP.25_5
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Hi.
I have another question about power series. I am having problem with the summarizing of the sum (writing in $\sum_{}^{}$ form).
Here is the question:
Let α be a real number that is not 0.
Let $$f(z)=e^{{\alpha}Ln(z+1)}$$
For integer n>0, find $$f^n(0).$$
My partial solution:
$$f(z)=e^{{\alpha}Ln(z+1)}=(z+1)^{\alpha}$$
$$f^1(z)=α(z+1)^{α-1}$$
$$f^2(z)=α(\alpha-1)(z+1)^{α-2}$$
$$f^3(z)=α(α-1)(α-2)(z+1)^{α-3}$$
The answer for $$f^n(z)$$ is
$$f^n(z)=\alpha(\alpha-1)...(\alpha-n+1)(z+1)^{\alpha-n}.$$
I am confused because when n=1,
$$f^1(z)=\alpha(z+1)^{\alpha-1}$$
but in the answer, there is the coefficient (α-1), this is where I am confused.
I have another question about power series. I am having problem with the summarizing of the sum (writing in $\sum_{}^{}$ form).
Here is the question:
Let α be a real number that is not 0.
Let $$f(z)=e^{{\alpha}Ln(z+1)}$$
For integer n>0, find $$f^n(0).$$
My partial solution:
$$f(z)=e^{{\alpha}Ln(z+1)}=(z+1)^{\alpha}$$
$$f^1(z)=α(z+1)^{α-1}$$
$$f^2(z)=α(\alpha-1)(z+1)^{α-2}$$
$$f^3(z)=α(α-1)(α-2)(z+1)^{α-3}$$
The answer for $$f^n(z)$$ is
$$f^n(z)=\alpha(\alpha-1)...(\alpha-n+1)(z+1)^{\alpha-n}.$$
I am confused because when n=1,
$$f^1(z)=\alpha(z+1)^{\alpha-1}$$
but in the answer, there is the coefficient (α-1), this is where I am confused.
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