0 to the complex power!

Algebra Level pending

If z C z\in \mathbb{C} and 0 z 0^z is a defined value (it is not undefined ) then what is the value of ( z ) \Im(z) ?

Notation: ( ) \Im (\cdot) denotes the imaginary part function .


The answer is 0.

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1 solution

Zakir Husain
Jul 23, 2020

Let's first compute 0 i 0^i x = e ln ( x ) x=e^{\ln(x)} x i = e i ln ( x ) x^i=e^{i\ln(x)} We know that e i θ = cos ( θ ) + i sin ( θ ) e^i\theta=\cos(\theta)+i\sin(\theta) x i = e i ln ( x ) = cos ( ln ( x ) ) + i sin ( ln ( x ) ) \Rightarrow x^i=e^{i\ln(x)}=\cos(\ln(x))+i\sin(\ln(x)) In the case x = 0 x=0 0 i = cos ( ln ( 0 ) ) + i sin ( ln ( 0 ) ) \Rightarrow 0^i=\cos(\ln(0))+i\sin(\ln(0)) And as ln ( 0 ) = u n d e f i n e d \ln(0)=\red{undefined} 0 i = u n d e f i n e d \Rightarrow 0^i=\red{undefined}

Now let's consider z = a + b i ; b 0 z=a+bi;b\neq0 0 z = 0 a × 0 b i = 0 × ( 0 i ) b = 0 × ( u n d e f i n e d ) b = u n d e f i n e d 0^z=0^a\times0^{bi}=0\times(0^i)^b=0\times(\red{undefined})^b=\red{undefined} ( z ) ( , 0 ) ( 0 , ) \Rightarrow \Im(z)\cancel{\in}(-\infty,0)\cup(0,\infty)

Now let's consider z = a + 0 × i = a z=a+0\times i=a ( z ) = 0 , z R \Rightarrow \Im(z)=0,\space z\in\mathbb{R} 0 z = 0 \Rightarrow 0^z=0

Therefore, if 0 z 0^z is not a undefined value then ( z ) = 0 \Im(z)=0

Same approach, although I think at first most would look for this.

Siddharth Chakravarty - 10 months, 3 weeks ago

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