Multiply the following expressions:

[tex]\left(4x^2 + 7x\right)\left(5x^2 - 3x\right)[/tex]

A. [tex]20x^4 + 35x^3 - 21x^2[/tex]

B. [tex]20x^4 + 23x^3 - 21x^2[/tex]

C. [tex]20x^4 + 35x^2 - 21x[/tex]

D. [tex]20x^4 + 23x^2 - 21x[/tex]

Answer :

To solve the problem of multiplying [tex]\((4x^2 + 7x)(5x^2 - 3x)\)[/tex], let's break it down step-by-step using the distributive property.

1. Multiply each term in the first expression by each term in the second expression:

- First term multiplication: [tex]\(4x^2 \times 5x^2 = 20x^4\)[/tex].

- Outer term multiplication: [tex]\(4x^2 \times (-3x) = -12x^3\)[/tex].

- Inner term multiplication: [tex]\(7x \times 5x^2 = 35x^3\)[/tex].

- Last term multiplication: [tex]\(7x \times (-3x) = -21x^2\)[/tex].

2. Combine like terms:

- The [tex]\(x^4\)[/tex] term stays as it is: [tex]\(20x^4\)[/tex].

- Combine the [tex]\(x^3\)[/tex] terms: [tex]\(-12x^3 + 35x^3 = 23x^3\)[/tex].

- The [tex]\(x^2\)[/tex] term stays as it is: [tex]\(-21x^2\)[/tex].

3. Write the final answer by putting it all together:

[tex]\[
20x^4 + 23x^3 - 21x^2
\][/tex]

Therefore, the correct option is B: [tex]\(20x^4 + 23x^3 - 21x^2\)[/tex].