Tell me more ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

How can I show for some transcendental number $\alpha \in \mathbb{C}$, that two distinct polynomials of the form $b_{n}\alpha^n + \cdot \cdot \cdot + b_{2}\alpha^2 + b_{1}\alpha$ and $a_{m}\alpha^m + \cdot \cdot \cdot + a_{2}\alpha^2 + a_{1}\alpha$ can never equal each other?

share|improve this question
2  
You should probably make explicit the assumption that the coefficients $a_i,b_i$ are algebraic numbers, since otherwise the assertion is not true. – Pete L. Clark Feb 21 '11 at 12:43
@Peter: of course, you're right. But I assume the OP meant transcendental over $\mathbb Q$, which is what unadorned "transcendental" usually means. – lhf Feb 22 '11 at 23:56

2 Answers

That follows directly from the definition of transcendental number: if $p(\alpha)=q(\alpha)$ then $p(\alpha)-q(\alpha)=0$.

share|improve this answer

HINT $\ \ $ By definition, $\rm\ \alpha\:$ is transcendental over $\rm\:F\ \iff\ F[x] \cong F[\alpha]\ $ via evaluation $\rm\ x\to \alpha\:.\ $ For example, $\rm\ \mathbb Q[\pi] \cong \mathbb Q[x]\:.\:$ Therefore, in particular, transcendental evaluation is always injective. Thus any element transcendental over a field $\rm\:F\:$ serves equally well as an "indeterminate" over $\rm\:F\:$.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.