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Which of the following is the correct factorization of the polynomial below?

[tex]\[ p^3 - 343q^3 \][/tex]

A. [tex]\((p - 49q)(p^2 + 7pq + 49q^2)\)[/tex]

B. [tex]\((p - 7q)(p^2 + 7pq + 49q^2)\)[/tex]

C. [tex]\((p^2 + 7q)(p^3 + 49pq + 7q^2)\)[/tex]

D. The polynomial is irreducible.


Sagot :

To factorize the polynomial [tex]\(p^3 - 343 q^3\)[/tex], we recognize it as a difference of cubes. The general formula for factoring a difference of cubes [tex]\(a^3 - b^3\)[/tex] is:

[tex]\[a^3 - b^3 = (a - b)(a^2 + ab + b^2)\][/tex]

Identify [tex]\(a^3 = p^3\)[/tex] and [tex]\(b^3 = 343 q^3\)[/tex]:
[tex]\[p^3 - 343 q^3\][/tex]

Recognize that [tex]\(343 q^3 = (7q)^3\)[/tex], which means:
[tex]\[p^3 - (7q)^3\][/tex]

Now, use the difference of cubes formula with [tex]\(a = p\)[/tex] and [tex]\(b = 7q\)[/tex]:

[tex]\[(p)^3 - (7q)^3 = (p - 7q)\left(p^2 + (p)(7q) + (7q)^2\right)\][/tex]

Expand the terms in the second factor:
[tex]\[ p^2 + (p)(7q) + (7q)^2 = p^2 + 7pq + 49q^2 \][/tex]

Thus, the factorization of the polynomial [tex]\(p^3 - 343 q^3\)[/tex] is:
[tex]\[ (p - 7q)(p^2 + 7pq + 49q^2) \][/tex]

Among the provided options, the correct factorization corresponds to:

B. [tex]\((p - 7q)(p^2 + 7pq + 49q^2)\)[/tex]