High School

Use polynomial identities to multiply [tex]\left(5-4x^3\right)\left(5+4x^3\right)[/tex].

A. [tex]25-4x^9[/tex]
B. [tex]25-40x^3+16x^6[/tex]
C. [tex]25-4x^6[/tex]
D. [tex]25-16x^6[/tex]

Answer :

To multiply [tex]\((5 - 4x^3)(5 + 4x^3)\)[/tex], we can use a well-known polynomial identity called the difference of squares. This identity states:

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

In our problem, let's identify the parts that match this identity:

- [tex]\(a = 5\)[/tex]
- [tex]\(b = 4x^3\)[/tex]

According to the difference of squares identity, we need to square both [tex]\(a\)[/tex] and [tex]\(b\)[/tex] and then subtract the square of [tex]\(b\)[/tex] from the square of [tex]\(a\)[/tex].

1. Calculate [tex]\(a^2\)[/tex]:
[tex]\[
a^2 = 5^2 = 25
\][/tex]

2. Calculate [tex]\(b^2\)[/tex]:
[tex]\[
b^2 = (4x^3)^2 = 16x^6
\][/tex]

3. Now, apply the difference of squares identity:
[tex]\[
(5 - 4x^3)(5 + 4x^3) = a^2 - b^2 = 25 - 16x^6
\][/tex]

Thus, the product of [tex]\((5 - 4x^3)(5 + 4x^3)\)[/tex] is:

[tex]\[
\boxed{25 - 16x^6}
\][/tex]

The correct answer is option D: [tex]\(25 - 16x^6\)[/tex].