How Does Solving P(x) Influence Q(x^2)?

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In summary, the statement "Prove $P(x)=0 \implies Q(x^2)=0 | POTW #485 Oct 4, 2021" is a conditional statement where the truth of Q(x^2)=0 depends on the truth of P(x)=0. P(x)=0 represents a polynomial function with a root at x=0. The proof of this statement involves using mathematical principles and techniques and can be illustrated with an example. This statement is important in mathematics as it demonstrates the relationship between two statements and allows for the use of proof by contrapositive.
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anemone
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Here is this week's POTW:

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Let $P(x)=x^3-2x+1$ and $Q(x)=x^3-4x^2+4x-1$. Show that if $P(r)=0$, then $Q(r^2)=0$.

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  • #2
Congratulations to the following members for their correct solution!(Cool)

1. kaliprasad
2. lfdahl

Solution from lfdahl:
Given $P(r) = r^3-2r+1 = 0$:

\[0 = [P(r)]^2 = \left [ r^3-2r+1 \right ]^2 \\\\ = r^6-4r^4+2r^3+4r^2-4r+1 \\\\ = \underbrace{r^6 - 4r^4 + 4r^2-1}_{= Q(r^2)} +\underbrace{2r^3-4r + 2}_{= 2P(r)} = Q(r^2)\;\;\;\; q.e.d.\]
 

Related to How Does Solving P(x) Influence Q(x^2)?

1. What does the notation "P(x)=0" mean?

The notation "P(x)=0" means that the polynomial function P(x) is equal to zero. In other words, all the terms in the polynomial have been simplified and the resulting expression equals zero.

2. How does the statement "P(x)=0" relate to "Q(x^2)=0"?

The statement "P(x)=0" implies that all values of x that make P(x) equal to zero are also solutions for Q(x^2)=0. This is because when x is squared, the resulting value will still make P(x) equal to zero.

3. Can you give an example of a polynomial function that satisfies "P(x)=0" but not "Q(x^2)=0"?

Yes, for example, let P(x) = x^2 - 4x + 4. This polynomial satisfies P(x)=0 when x=2, but it does not satisfy Q(x^2)=0 when x=2, as Q(x^2) would result in a non-zero value.

4. How can you prove "P(x)=0 \implies Q(x^2)=0"?

To prove "P(x)=0 \implies Q(x^2)=0", you can use a direct proof by assuming that P(x)=0 and then showing that this implies Q(x^2)=0. This can be done by substituting x^2 for x in P(x) and simplifying the resulting expression to show that it equals zero.

5. What implications does this statement have in mathematics and science?

This statement has implications in various areas of mathematics and science, particularly in the fields of algebra, calculus, and physics. It can be used to solve equations and systems of equations, as well as to prove theorems and make mathematical predictions. In science, this statement can be applied to model and analyze real-world phenomena, such as in physics equations that involve polynomial functions and their solutions.

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